^ I was in your situation not too long ago. Thinking back, I think I was only asked 2 core questions:
-Why accounting? <-- major topic of interview
-How do you think you'll do in our program?
Minor things that I remember:
-Why did you choose your email address and what is the meaning behind it? <---
-How did you study for the GMAT?
The interview process at USC (in my opinion) is more of an assessment of the candidate's sanity--it's their way of making sure you are not a lunatic/psycho. I think it stops there. I don't think the interview process significantly influences the candidate's chances of getting in (unless, again, you are just obviously dumb or crazy). A grad student gave me a tour after the interview and he said that his interview last year lasted less than 5 mins on the phone, which supports my hypothesis in my opinion.
Good luck.