I honestly don't know... Hmm. I would think that you should have the option of interviewing them first, only seems right since you're paying them for a service. But in OB world things are mighty different than in midwives world.
I would highly suggest that when you do meet the OB, you lay out exactly what you are expecting from him/her. Don't beat around the bush about anything. Have it all written down, so you don't forget anything, and make sure he/she realizes you are not an idiot, that you are in fact very educated on your rights, and what you will and will not tolerate. From experience, I know that OB's tend to be intimidating and act like they are the only ones that know how to do any of this birth stuff. Not that they're all like that, just some. I think it's good to go in prepared. And if anything doesn't feel right with the way they answer your questions... Listen to your gut. You will find the right OB, but you need to be ready to look for him/her.
I hope that all made sense! And I wish you all the luck in the world! 
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