Good luck in your interview. I would always err on the side of formality, and wear a suit to any
interview. On the "General Nursing Student" board, there is a sticky thread regarding nursing school
interviews, with a lot of great tips to help you prepare.
I hear your point about prior preparation and unfair advantages, but I think it's different than, say, the OHSU proctored essay, where you are required to agree not to disclose the subject of the essay. I haven't interviewed at U of P, but I suspect the questions are not static, and are typical of nursing school interviews.