Ugh...interviewing T's is tough.
Here is a good article: How to find a good therapist
it helped me a lot.

Some important questions:

What is your approach to therapy?
How much experience do have dealing with ______? (your immediate issues)

What are your boundaries regarding contact in between sessions?
How difficult is it to schedule appointments?
Would I have a weekly standing appt or a floating one?

It is also good to make a list of things that have helped and things that have not helped previously in therapy and have that handy.

Welcome to PC...I hope this helps. Let us know how it goes!