1. You have real freedom of speech. If you don't like Jews, you can say so. Think women are lazy, have your say. As long as you have a point to make and are willing to actually introduce an intellectual standpoint behind whatever it is, you can say so. That doesn't mean you can write racial slurs and just leave it at that. But if you wanted to discuss say the link between IQ and race and bring real examples and data, that's a debate you can have here.
2. I found it, much like everyone else does. Learned more about it. Became more interested.
3. Too numerous to recount, but they involve real world debates, encounters, media and visiting education establishments. I have also generated vast amounts of maps, uncovered documents and made things available. It is unlikely you could google "flat earth" on an image search and not see some of my content.
4. Zero. I don't give two hoots what other people think. Show me something, make it interesting, I'll learn from it even if it isn't true, I still have to work out why. Keeps the old grey matter ticking.
Good luck with your course.