SDave03, most BM’s in performance will want a narrower focus. On the other hand, a BA is a more academic degree, and may even have little performance in the curriculum. Lessons and performance opportunities may be available but as extracurriculars at some schools.
Composition can be done in either a BM or a BA program.
You can major in anything and still go to med school. Either take prereq’s during college or, as mentioned above, in a post-grad program.