One faculty interview was open file. The other faculty interviewer and the student interviewer just had access to our Personal Statements. I believe most interview dates only have two interviews so I'd guess it would be one of each (ours was structured a little differently and they let us know that). I didn't see any opportunity or find it necessary to have anything extra. If I had brought something I was determined to show I think I would have had to make an obvious effort to fit it in to the interview. However, that's just my opinion based on my interviews. As always, it's never a bad idea to review your application and personal statement before attending the interview to make sure what's on the application you may have submitted quite a while ago is fresh in your mind.
If you need to update coursework/prereqs you'd have to send an official transcript anyway, so bringing it with you wouldn't do much good. If you have questions about the prereqs you still need you can always call, but Dr. Ancajas was nice enough to double check something I had a question about the day of the interview.
Also, they gave us a folder with lots of information and a pen so it was easy to take notes and keep track of information. I wish I hadn't brought a padfolio as it just gave me one more thing to keep track of. Good luck!!!