I agress with elk park - "Nurse midwifery in the US is a graduate degree program". I don't think you would be able to combine a bachelors level midwifery degree and an RN degree. But this website might help with some of your questions about nursing education- http://www.medicalandnursing-training.com/. You also might consider calling a few nursing schools to see if you can get an actual person on the phone who can give you a more concrete answer.
I hope that helps!