Yep there was an ethical essay, wasn't too difficult. It seems everyone in my group had the same question, but I'm not sure If they change it based on your interview day.
As for questions, I think it depends on which faculty interviewer you get, which you will only know the day of. I had to take the shuttle to the hospital, where my interviewer was. He took me to see 2 patients with him, which was definitely out of left field, and the actual interview lasted around 10 minutes. He did ask my about the state of the medical field, and the most significant problems in medicine right now.