Most peoples interviews for my class were chill, essentially, welcome to Sackler. Mine perhaps was the same, but I was asked some pretty tough/standard med school interview questions. After nailing one of them she dropped it and asked me if I had questions for her. I asked some solid questions about how safe she felt, how easy it was to get to the hospitals, how was the language barrier.
As for 30 year old physicians teaching you, thats of course your 3rd year. In the past, an interview was a very good sign. But apparently the program is competitive so bring your A game to the interview.
Oh, and as far as cut throat students, they exist in every class. There are people who care far too much about certain aspects of their education, but really they have no impact on your own success.