aspiringdoc, I am an RN who worked for about six years before returning to medical school and will try to address some of your questions. First, you asked if being a nurse works against you in you medical school application. That was certainly not the case with me, and I seriously doubt it occurs often, if at all. Med schools (at least allopathic one--not sure about osteo schools) are primarily interested in MCAT scores/gpa, because statistically speaking, these are a good barometer of how you will do in med school (NOT necessarily of how good of a doctor you will be). So bottom line: good MCATs and grades will get you an interview, and once you get an interview you need good interpersonal skills to get accepted.
As far as the BSN program you are speaking of--I love nursing and would not have done my schooling any differently if I had it to do over, but I am not completely understanding why you are wanting to get your BSN. If you are hoping to work your way through Med School, that probably isn't going to happen because med school is really, really demanding. I worked (and still work) SOME, but not enough to significantly decrease my loans. I promise med school will wear you out, and you won't work as much as you may think you will (especially if you have family). So in the two years to get your BSN, you could have a pretty good jump on at least the prereqs for med school. . .Anyway, just something to think about.
Good luck.