As a counterpoint to people asking about research, nobody asked me about research on the interview trail because I didn't do any.
I did get asked, with some frequency, where I saw myself in x years. They wanted to get a sense that I had some coherent career goals that maybe even extended beyond FELLOWSHIP: YES/NO
It was also common to ask why I applied at that program. Since the answer was "because you're an academic program close enough to drive to that has a decent reputation", I tried to spruce it up by drawing on their morning presentation.
If you forget to do any research before interview day, lemme tell you: they hand you a bunch of questions to ask them when they're describing their program, and give you plenty of things to talk about.