> Ask a question in a lecture? The 100+ other people in the room are now staring at you like you're an idiot, despite the fact that most probably have the same question.

I always ask the question anyway. The lecturers don't mind answering questions -- they're there to teach you (though since I talk to them outside lectures, I might have a different view of how lecturers feel about students). Even if it's a dumb question, just ask. People who judge you for asking a question are assholes and aren't worth your time.