How does healing work?

Here’s some excerpts from an article I had published elsewhere (I forget where). It helps define how I as a GM handle healing. This isn’t necessarily the rules of Legend Quest, just the rules of me:

First, healers can only heal diseases that they can identify. This prevents a healer from casting cure spells on a person not known to be sick. The magic may be powerful, but it must be directed. This means that healers must have some knowledge of medicine or physiology. The healer does not need to know the name of the disease, but he or she must recognize that the disease is there.
The ultimate question seems to be, can magic cure cancer once it has started to spread? The quick answer is, no. Chances are, a healer would not identify a disease like cancer in its early stages. Perhaps the healer might be able to cure a cancer “lump” and prevent the disease from spreading, but if it were to spread, the patient would be doomed. As the disease attacked different parts of the body, the healer might be able to cure pieces of the disease, but would not be able to keep up. When the disease had taken hold of the bones or internal organs, the healer might not be able to identify enough of the disease to cure it.
Cancer is just an example. Many of the medieval plagues might be much easier to cure. Most of them were accompanied by symptoms that could be seen on the skin. It would be much easier for a healer to see and cure the disease that causes large, red splotches than the disease that weakens bones.

Building on Necromantic Surgery - What about spells that will transfer the soul of a person into someone else’s body? I frequently think of taking some old, brilliant (and evil) wizard and transferring his mind into the body of some 20 year old athlete. Boom! Now he has the best of both sets of attributes. No longer a quick kill, he’s now attractive and a pro-wrestler.