"Second question: is it ethical for a student to disrupt class discussion with political grandstanding?"

Simone Weil thought that all ethics, and even all religions, ultimately amounted to the same thing once they were properly understood. She pointed out that there were certain similarities between every moral system history. For example, every religious and moral system has always said that if a rich man walks by a poor and starving man, he is obligating to give him money and food. Another interesting one is that every moral system agrees that people in power should be punished for moral digressions more than people without power and responsibility. For example, more or less everyone agrees that a coach should be punished for cheating more than a player, because they have more power and authority, so their cheating is a higher level of corruption.
Weirdly, when we look at actual societies, these universally agreed upon moral rules have never been applied. For example, in every society there have been rich men and staving poor who go unhelped. In every society the rich and powerful get away with crimes far more than the powerless masses. Why the disconnect? It's almost enough to make you think society is not organized around moral principles.

Also though happiness itself leads to despair, so watch out for that.

The Ancient Stoics all more or less agreed that you should live a life devoted to virtue and civic duty, and yet mysteriously this part of it seems to get cut out of 98% of Stoic Gurus today.

Stoicism has attracted a large amount of self-aggrandizing grifters, all of the examples are from real things I've seen, including the story about a bomber pilot in Vietnam who kept a copy of Epictetus in the plane, which was presented unironically as cool and badass. Here is a little tip: if someone talks to you about Stoicism and only presents it as a kind of "tool" to help you get what you want, and doesn't talk at all about virtue ethics and civic duty, they aren't talking about Stoicism. If you don't become a better person, specifically in your relation to the world and to other people, after studying Stoicism, you have made a mistake. A lot of young people seem to even become worse people. More selfish, more self-important, and less concerned with the feelings of others.
If you are actually interested in Stoic Philosophy, then for the love of god just listen to someone who cares about the philosophy in and of itself, like Massimo Pigliucci or Greg Sadler.

Incredible coincidence that these effective altruist/longtermism dorks are always rich white guys living comfortably on the backs of the poorest and most exploited by the system, and they've discovered what is best for the world, and indeed the entire future of the human race, is to continue as is but give like 12% of their paychecks to charity or something.

Longtermism is a rather silly branch of "effective altruism", where philosophers try to work out what we should do to maximize the happiness of humans in the very long term. While it's an interesting idea to talk about, for whatever reason it tend to attract a bunch of people who seemingly want to use it to justify their place in a hierarchy today. For example, they will make a lot of money off exploiting people, and justify it in that they are donating some small part back to "long term" problems. Dismantling the system itself which exploits people, of course, isn't part of it. Even weirder, it attracts kind of AI conspiracy theorists who watched too many Terminator movies and think we have to stop super intelligent AI from doing...something bad.
If you really want to help the long term future of humanity, you should probably just become a communist like a normal person.

"Also there was a previous comic about de Beauvoir as 'Ambiguity Woman' who seemed to think ambiguity is good, so that makes it more confusing..."

While existential philosophers never directly talked about whether that was a valid meaning of life, Camus at least strongly hinted that it was.