My D hasn’t said anything about the facebook chat except that everyone seems super friendly and happy and eager to meet future classmates, but I can see it could be intimidating especially if you are from a different culture socially.
I think the biggest thing is to just have respect for human dignity and a sense of empathy for the other humans you are sharing the planet with. As long as “not agreeing with their mottos” and “politically incorrect humor” won’t involve using racial slurs or feeling a sense of contempt for anyone different from you, you’ll be fine.