FPs don't get the best pay in the field but they get work fairly reliably. They also seem to sort of be their own breed of person. You likely have to move though, unless you're in a big city. Whether you do crime scene stuff or simply do the autopsies depends on your state (or county).
There are autopsy technicians and the sort that may do the cutting and related paperwork. They're not doing the reports or investigations. At fullest capacity, they're making all the incisions and pulling out all the organs for you, unless you request otherwise. They're not usually trained PAs, since that's sort of different field. A good one is worth his/her weight in gold, but it may not be all that fulfilling.
Pure pathology assistants are found more in surgical pathology labs than autopsy bays. They do the majority of the grossing, and many cut frozens, but no scope work. If you like looking and orienting specimens, it's cool and pays well. If you want to make a diagnosis on the living or put together the pieces of a forensic autopsy and determine cause and manner of death, that's MD stuff.