What are some tips for dining in France without accidentally breaking any unspoken rules, like mixing salad and main dish on the same plate?

Would you encourage your vegan friends to stay vegan if humankind becomes forced to exclusively utilize Pleistocene, Neolithic, and BCE technology and infrastructure?
Why do sentient beings withhold information from people when they could have said something or done something to help them. Do people think they're God? Where is the forgiveness and love amongst strangers who are actually best Friends and family?