Also, while sarcastic, he had a point. Don't bring up those other topics at interview dinners. You never know who's going to take something the wrong way, and I can tell you that most of your colleagues are not going to have similar viewpoints to you. I would say stick to things like sports, but that might derail quickly. So maybe stick to safe stuff like movies, the geography, hobbies, etc.
Wear a button-down and slacks, even if the invite says jeans. It's never over-dressing, and you don't want to be the least dressed person there. Have 0, 1, or maybe at most 2 drinks if the event goes on for awhile. Some residents may take it as the opportunity to get sloshed, resist the urge to follow suit. Nothing you do at the dinner is going to guarantee your acceptance, but some things at the dinner will guarantee your rejection.