Corpsman A School was at one time conducted at both NSHS San Diego and NSHS Great Lakes, they closed the San Diego A school sometime in the late 90's well after I was in the fleet.
At Ft. Sam when I went through 91B was pretty much a 14 week EMT Basic class. We weren't allowed to do anything on our own when I got to my unit.
When I left Corps School I was suture trained, had basic x-ray, lab, ortho and surgical experience. The philosophies were different between Army and Navy medicine, in the fleet some duty stations there are no doctors, pa's nothing- you mr. petty officer 2nd class Hospital Corpsman are it..... write scripts, do all diagnostics, do all treatments on your own or maybe with a junior corpsman.
The rest of the schools after that were just more intensive tactical and medical skills courses.