Hey guys,
Congratulations on getting interviews (waitlisted)... I'm currently a first year, so preparing for interviews is still pretty fresh in my memory. The best advice I can give is be prepared and look/act professional. Know the APTA inside and out (ie. what it is, the core values, vision 20/20, etc). Also, familiarize yourself with the current affairs of PT (like what issues are in legislation, both national and at your state level, etc.). You also want to start thinking about situations in your life where you were challenged, times where you had to be a leader, and other typical interview questions. Just do a search on here for example interview questions because there are plenty of them that are helpful in preparation. If you can, wear a suit and just try to be yourself.
Good luck!