I think you made like 4 or 5 threads about USC's interview.
Nothing will prepare you for an interview. No amount of preparing will give you a leg up in the process. From what I have seen at all eight of mine, is:
They are strictly evaluating your personality. They want to accept people that are going to be fun to have around for 4 years. I have seen SOOOOOOOO many gunners at my interview days and you can tell the administration are put off my their over-zealousness. Just be talkative and personable throughout the day and especially during the interview/evaluation portion and you'll be fine.
I mean think about it, if they are not just "evaluating your personality" they would just ask all of their interview questions in a secondary and you would have no need to come in. USC is, as you have heard, just evaluating how your work in a group, which is basically an evaluation of your personality+people skills.
At USC, the interview day makes you feel like a number. You are in a room with 30 other applicants and they will only evaluate you in a group of 8 (minimum). I mean.... they give their welcome speech and your folders in this weird hallway and then they give the rest of your presentations in a tiny room. They charge the most to their students for the dental education and yet they were the ONLY school out of all 8 that I went to that did not have refreshments... We were told to go buy water bottles on our 5 minute break. When you charge a half-million per student, you can afford to make a better impression on the students considering your school. However, USC has perks.... Living in LA and PBL (if that is your sort of learning style). That is it. If you go to USC for any other reason it is because that is the only school you got into. You can find everything that USC has to offer at other schools.
USC knows it is the mother of back-up schools. You could hear it in the tone of each presentation. They were trying to "sell" a future at USC, rather than let the program speak for itself.
In the end, if I am at USC next year, I will be happy because I know that I am four years away from fulfilling a life-long dream.... But I will also know that I had no other options.
Also, USC's football team is starting to not be a selling point...