The questions you asked about the appt are some that you will ask the Doctor
Session length is usually 50 minutes, but that's up to what your T does. T might shorten the session some, and reduce the fee. Be sure to discuss your concerns upfront with the T.

I think it's mainly a get to know each other a bit, to make sure it's a good fit. What type of problems you want help with and what type of therapy the T gives are two other things to discuss, imo.

Ask about contact between appointments. Does T have a secretary every day during week or not at all? Can you leave voice messages, emails etc as you need to, or not? What would your T like to be called (some prefer first names) and what are you comfortable calling your T?

Please keep in mind that this is someone you are hiring to consult with...just like you had a project or a business that you needed advice about. TC!