In "The Fixation of Belief," American philosopher Charles Sanders Pierce distinguishes various methods people use to fix their beliefs. Two of these are related to the phenomena you describe: the "method of tenacity" (where people hang on to beliefs even against piles of evidence) and the "method of authority" (where people form and revise their beliefs on the basis of the beliefs that certain others hold or express). You can read this essay at www.peirce.org/writings/p107.html
Yes, there are seminal works of philosophy that are of historical and systematic interest for the understanding they convey of what philosophy is. Here I would mention at least a dozen historical works before any more recent academic papers - works by the usual suspects: Plato, Aristotle, Descartes, Hobbes, Locke, Hume Rousseau, Kant, Hegel, Marx, Mill, Frege, and Wittgenstein. With regard to academic papers - by which I take you to mean shorter works published in the last 60 years or so - there is no settled canon. Still, it is pretty clear who have been the leading philosophers of this period; and pretty clear also, in most cases, what their most important essays were. It would be difficult to understand the current state of Anglophone philosophy without having read at least a good smattering of the following: W.V.O. Quine's "Two Dogmas of Empiricism" and "Epistemology Naturalized", Donald Davidson's "On the Very Idea of a Conceptual Scheme", Philippa Foot's "The Problem of Abortion and the Doctrine of Double Effect", Robert Nozick's "Coercion", Derek Parfit's "Personal Identity" and "Equality or Priority", Tom Nagel's "What is it Like to be a Bat?", Bernard Williams' "Moral Luck", Ronald Dworkin's "Taking Rights Seriously", Peter Singer's "Famine, Affluence, and Morality" and a few other seminal works by Elizabeth Anscombe, Ruth Marcus, Saul Kripke, Hilary Putnam, David Lewis, Thomas Kuhns, John Rawls, John McDowell, Jerry Fodor, Patricia Churchland, Dan Dennett, and part-timers Noam Chomsky and Amartya Sen.
Insofar as pupils have the same human rights as adults do, your argument is compelling. If we did to adults what we are doing to adolescents, we'd be violating their human rights.
An obvious defense of our education system (BTW, non-Western ones are not much different and mostly more restrictive) would claim that each person's human rights become more extensive as they grow up and that mandatory schooling of people below a certain age does not violate the narrower set of human rights they already have. There is surely something to this story: a mother is not violating a human right of her toddler when she prevents him from exiting down the stairs -- the toddler does not yet have the relevant human right to freedom of movement (though he already does have the human right not to be killed). But can this be developed into a defense of forcing a 14-year-old to attend school?
There's amazingly little serious work on this general question: on what competences and capacities children must possess in order to have this or that (component of a) human right. One important aspect of this general question is the extent to which the law may generalize, that is, may tie the rights of children to their age. Some people are more mature at 14 than others are at 18 -- and can it be legitimate to deny the former the full protection of human rights as afforded to the latter? Would this not be as wrong, and for the same reason, as it would be to place special restrictions on male adults with two Y chromosomes on the ground that they are more likely to commit violent crimes?
Another important aspect of the question is how serious coercion and punishment must be for them to constitute a human rights violation. Clearly, shackling someone to a chair in a classroom constitutes a violation of the human right to freedom of movement, and so would the credible threat of a month in jail for non-attendance. But we don't actually go this far. Are milder punishments acceptable? What actually happens when your teacher denies permission to go to the bathroom and you go anyway? If the sanctions are mild, they may not violate human rights even on the assumption that the pupil has the same human rights as an adult. For example, well into adulthood, I had to take various classes as a condition of my employment: classes about proper conduct in the workplace and about how to handle fire emergencies, among others. Had I refused, I might well have lost my job. Did my employer violate my human rights? If not, then your school might argue, in parallel, that it is not violating your human rights by requiring you to attend classes on pain of suspension or even expulsion. "You have no human right to attend this school on your own terms," it might say, "you are free to stay away but, if you do choose to come, then you have to accept our terms."
To be sure, this sort of argument can only go so far. Not allowing pupils to go to the bathroom is wrong even if these pupils have the option of not being in school at all -- no less wrong than would be not allowing workers to go to the bathroom when these workers have the option of resigning their job and losing their income.
As you can see, there is a lot to be thought about here; it's a superb topic for further study.
And I'll chime in with my favorite: Okasha, Samir (2002), Philosophy of Science: A Very Short Introduction (Oxford University Press), which I think is a terrific survey and lives up to its title of being "very short". I'd also agree that it's probably best to look at a survey such as the Stanford Encyclopedia of Philosophy article, or something like Okasha's book, before diving into one of the classics.
Sure, you can become a teacher of philosophy -- most plausibly in a college or university (with a PhD), or perhaps also in a highschool (with a MA). There's not much else, though, for professional philosophers. But then you can also choose another career and keep up with some of what philosophers do as a hobby....
There is a great influence, of course. But it is subtle and impossible to understand simply by reading ancient philosophers. It makes more sense for you to prepare yourself by reading contemporary works that give you a sense of how citizens in the affluent Western countries think about themselves, their relations to the rest of the world, their history, and the world's future. These contemporary works will be more accessible to you, because you understand much better the context in which they were written than you can hope to understand the context in which Plato wrote. And you can still, in a few years, do some study of the ancients if you are so inclined. For now, I would try to find a textbook collection of contemporary essays on ethics or political philosophy, and then learn about the debates we have here about affirmative action, the environment, equality for women, war, poverty, trade, and so on. (By the way, I would give analogous advice to a young Western student departing for a year in China. She should read up on some of the current debates in China and leave the great Chinese classics for later.)
Your experience may be more reflective of philosophy in Germany than of philosophy more generally. There are at least three relevant factors. German students specialize early while students in the US, say, take a broad range of courses in diverse fields during their undergraduate studies. In particular, they take broad (often mandatory) Western civilization courses that focus on philosophical materials that (i) integrate well with non-philosophical materials produced at or around the same time and (ii) are attractive and helpful to students through their relevance to present society. This relates to the second point, that universities in the US tend to reward (often quite directly) teachers and departments for attracting students; and it's rather easier to attract undergraduates to feminist themes than to, say, the philosophy of language. All this in turn reinforces the third point that German academic philosophy tends to be a bit narrow and conservative.
While feminism certainly has a presence in US universities, it tends to be segregated. We have women's studies departments, for instance, and the occasional philosophy course on feminism. Yet gender issues are still not well integrated into courses on moral and political philosophy, professional ethics, and the like. And likewise for philosophical publications. There are some very good feminist writings, but virtually all the major books on moral and political philosophy, professional ethics, and the like ignore the very interesting issues raised by the systematically differential life chances women and men have in virtually all existing societies.
For an accessible discussion of who else has written on this topic, I would recommend Susan Okin's books Women in Western Political Thought and Justice, Gender, and the Family. The former deals with some older, the latter with some more recent treatments of the subject (both feminist and anti-feminist). You can probably also find out a great deal through the internet. One easy way to start is with the Stanford Encyclopedia of Philosophy (plato.stanford.edu/entries/feminism-topics/ with various subentries). But I also found a lot of interesting stuff through a google search for (jointly) feminism and philosophy.
More than on your preferences, the answers also depend on the kind of students you face and on the legal system within which they serve. In light of my limited knowledge of these and other relevant matters, I would suggest you focus on leading your students to think philosophically about the law. For example, what moral authority do those in government have to enforce laws against non-consenters? What must the government be like, and what must the laws it is enforcing be like, for such enforcement to be morally permissible? And under what conditions does the mere fact that something is the law give citizens a moral (as opposed to a merely prudential) reason to act accordingly?
These sort of questions and reflections are crucial, I think, for students to appreciate the conceptual gap between the law and justice -- a gap that is often deliberately obscured, as when the government agency in charge of law enforcement is called the Department of Justice (its recent head in the US, Attorney General Alberto Gonzales, authorized torture) and judges are referred to as justices. Being aware of this gap helps future lawyers to be sensitive to the responsibilities they bear, as officers of the law, for its broad conformity to justice.
Such broad conformity is endangered when lawyers and other officials act "under color of law," i.e. abuse their legal authority for personal ends. And such broad conformity is even more seriously endangered when the entire legal system is perverted in the service of a blatantly unjust regime, as arguably happened during Brazil's two decades of military dictatorship. As St. Augustin famously said (in somewhat different words), without justice a well-ordered legal system may be no better than organized robbery and exploitation. Such perversion is, of course, a matter of degree. And so the lawyer's responsibility always involves helping to make the legal system one that really has moral authority to command and really does generate moral obligations to comply. In Brazil, as in most other countries, a great deal remains to be done, and lawyers can play an important role in promoting not merely the rule of law, but the rule of just law.
There are the classic authors: Plato, Rousseau, and John Dewey.
Among contemporaries, I would name Nicholas Burbules (pragmatist), Harvey Siegel (analytic philosopher), and Joseph Dunne (Gadamerian).
Given your background in political science, you might also want to look at Paulo Freire for critical pedagogy and at Meira Levinson's The Demands of Liberal Education. This is a really well-written book on the education of personal autonomy in liberal society. For placing the philosophy of education into the wider context of political thought, you might look also at Amy Gutman's work. Formerly a political scientist, she is now President of the University Pennsylvania.