This sounds like having some useful additions to famous Morph Merger!
I will definitely give this a try!
Question: I don't know how the seperation of head an body is done... are you specify some vertices coordinates?
Would it maybe be possible to seperate the mesh in even more parts?
Maybe it is only me, but sometimes I would like to exchange other body parts, too, like hip, feet, legs, breasts, arms, shoulders... Your "auto fix height" could maybe work on such parts, too?
Unfortunately the "normal" tools like Morph Mass Manager doesn't work with mixing allready merged morphs.
But I guess this will come with other unpleasant issues like arms being thinner than shoulders or hands, for instance.
So this is most likely a bad idea.