I have been in the OR for ten years. I think you have a great plan to start (I went straight to the OR after nursing school). You will need at least a year like the other replies to get "used to" the OR. It is a different animal. RNFA is a great job that makes great money. The downside (at least at my hospital) is that usually one of the RNFAs are out due to illness, personal, whatever it may be. In that case you might end up on call every other night (again, depending on where you are). The RNFAs at my facility take a LOT of call which is why they make great money. We do have one PA that works with one of the surgeon's here in the OR. I am in a smaller community, but it is not unheard of to have NPs or PAs in surgery. I was contemplating an RNFA program myself after I get my NP.
I have nine months left of my NP program. I think my program is great. Yes, some days I feel completely stupid and wonder what the hell I am doing. I felt that because I was in the OR I would not do as well, but that is not the case. A lot of people share the same fears. It is like nursing school; it is not that the concepts are hard....it is just what you put into it. I have heard and spoken with plenty of NPs and PAs. They ALL felt this way in their programs.
My preceptors each semester have told me I will make a great NP and are impressed with my knowledge base, so not that I am feeling cocky, but I would not believe the hype about being "underprepared." It is a huge change. You are now diagnosing and doling out orders rather than following them. You could KILL someone. Of course that is scary! I kind of thought the same thing about NP versus PA..."well I am already a nurse so I may as well go NP." I think either would be fine but that's all up to you. Seems like you already know that hospitals in your area accept ACNP over FNP so I don't really feel like you will be missing out by going ACNP route. That does not matter where I am.
I have really enjoyed my NP program and am learning a lot. It is doable. I am not a type A personality (no offense if you are) and I have not always been an A student. I really worked my a$$ off this semester and pulled two As. It has definitely been challenging but I want to be the best I can be to provide solid care. Once clinicals started, I went per diem at work which really helped. If you can swing that or not working at all I would highly recommend that. If you are really passionate about the OR give it a little time. If you want to be an NP in surgery, you will be able to make it happen.