Hi,
I just did a group interview for Loma Linda's MFT program yesterday...I thought it would be somehow more intimidating than a one-on-one interview, but I actually liked it better. I'm not sure if yours will require you to answer the questions in the order of the circle or if you can just answer randomly. But if you can just answer when you feel ready, it's an advantage over the traditional one-on-one interview because you have more time to think of your responses, and you can get ideas of how to answer based on others' responses and relate to what others are saying. The only awkward part for me was that it was three one hour long interviews with the same group of people, but different faculty members each time. So we had to keep repeating our same answers that everyone in the group had already heard. Hopefully you don't have to deal with that for yours, but if you do, it's really not a huge deal anyway.
I haven't done any one-on-one faculty interviews yet, but I would just suggest the common sense approach of thinking of some typical questions they may ask you and prepare an answer for them ahead of time. One admissions counselor told me that I might be asked who my favorite theorist is and why, but that was for a psy.d program, so I'm not sure if an MFT program would ask the same. I'm not sure if you have the group interview before the faculty interview, but if you do, that should be helpful because the group interview will give you a good feel for what to expect and good practice in how to answer.
Hope that helps! Good luck!
Can I ask, which schools have you been invited to interview for?