agree with acetabulum.
Your answer to "why ortho" does not have to wow anyone. Be honest and describe what attracted you to orthopedics. Don't try to be unusual, eccentric or funny. Be sincere. There's no right answer to this question. They want to know if your reasons are genuine and not superficial.
As far as the questions, this was the most difficult part of the interview for me. I went on so many interviews, and after the first 3 or 4, I did not bother to do research on the programs cause i was just tired of the whole process. Ask generic and NONTHREATENING questions. Again, don't try to be unusual or unique. Ask standard questions that everyone else probably asks too, but look interested when they answer. I asked the same questions on every interview....multiple times on the same day.
Don't ask questions that would make the program or the interviewer look bad. For example, if you know they don't offer elective time, don't ask them if they do. If you know they're not heavy on research, don't ask them about their animal lab, etc.
I focused on 3 areas, and revised the question depending on where i was:
1. Research
2. Future direction (any changes they anticipate in the next 5 yrs, etc.. see acetabulum's post)
3. Strengths/weaknesses of the program