I had this and was on bed rest for five weeks. Mine was diagnosed earlier, though -- at 15 weeks. By my 20-week ultrasound it had completely resolved, and I was very active for the remainder of my pregnancy. I actually switched to a midwife AFTER the whole previa thing because I was uncomfortable with the course of action the diagnosing OB had planned. I had a completely natural (not induced, not medicated) delivery, but in a midwife-friendly hospital, not at home.
While the previa thing was going on, I never switched to a high-risk ob/perinatologist, nor did anyone recommend that I do so.
I was also never told that a vaginal ultrasound would be contraindicated with placenta previa. That doesn't mean that it ISN'T, just that I personally have never heard that before.
Really, the thing to remember with previas is that the majority go away on their own, with no complications. For the minority of people whose previas don't resolve, you are looking at a high-risk pregnancy, with a c-section, but that's a small percentage. Statistically, I think you have good reason to be optimistic, and you can always switch back to a midwife if things work out. I would probably recommend being realistic about the possibility of a c-section if it doesn't, though, just in case.