First, keep in mind that YOU are interviewing them. You are the employer. They will be working for you. (Yes, I know that seems strange since you are paying for their services) THEY need to earn your trust. And, if they don't answer all of the questions you have to your satisfaction, look elsewhere!
Here are some websites that could help you with questions:
https://medcircle.com/articles/questions-to-ask-a-new-therapist/
https://www.health.harvard.edu/depression/10-questions-to-ask-when-choosing-a-therapist
https://www.huffpost.com/entry/questions-therapist-first-session_l_5d165604e4b082e55368cc5f
When I started seeing a therapist (really a psychiatrist) last year, I grilled him. One question I asked which helped me was, "I have been practicing law for 37 years. If a run of the mill, small case comes in, I am going to turn it away. There is no challenge there, I will get bored and not do my best work. If you believe you will not be challenged by me, I need to know. You have been doing your work a long time and have probably heard everything. So, I need to know what about our relationship you believe will challenge you."
As for finding a therapist, there a number of websites. You can start with this one though:
https://www.findatherapist.com/search/
goodtherapy.org is also an ok place to start looking.