Necromancy, by its very name, has to do with death. So it's a perfect school for speaking with dead, animating dead, bringing the dead back to life, and so on.
I don't agree with it being a "medecine" school, though. Not the same thing.
And I have no problems with earthquake being evocation. Calling it from another dimension would be conjuration. See that earthquake as a special form of telekinesis.
Since healing is through positive energy, and evocation is the energy school, then healing should be a subschool of evocation, not of conjuration.