I'll chip in a bit of knowledge on the weighting/rigging...
To my understanding:
"Weighting" is the act of setting the weight of a vertex or series of vertices, which in turn determines how much those vertices are affected when their parent element (for example, the hand [not the fingers or thumb, essentially just the palm] would be parented to the lower section of the arm in the original models).
"Rigging" is the act of adding "bones" to a model and setting them up as the parents of a series of elements, such that when the "bone" is moved, anything parented to that "bone" will be affected, though the amount to which it is affected is determined by the weights of the affected element's vertices.
Now, if I'm wrong on any of that, please correct me.
For the KotOR games, a regular character or head model will include: the pieces seen in-game, invisible "hooks" (such as the camera hook, right and left hand hooks, the impact hook, or a goggle hook), and lastly invisible pieces of geometry. These are invisible because they have no texture applied to them, so nothing is "rendered" in-game. These invisible pieces of geometry are KotOR's "bones" and it is these "bones" that are actually animated, with the real in-game geometry being parented to these "bones" and weighted so that the geometry is realistically affected.
The developers used a series of five models that house the master list of animations: s_male01, s_male02, s_female01, s_female02, and s_female03. Together, these models contain every combat, dialog, and movement animation used by a humanoid NPC. This is done by the models themselves having nothing but the hooks and "bone" geometry in them, and the models that need these animations "linking" to these "super models" in their compiled form.
For most of the heads in the game (AKA, any head that is just a head, not attached to a body as a one-piece set so-to-speak), they link to one of these super models, commonly s_female03 (which in itself links to s_female02, which links to the 01 and then the chain continues back to s_male02 and that one includes s_male01), and so gets the animation data from there. The common exception to this is the party member heads, which seems to link back to their normal clothing models (the "BB" models).
Given your task and the specific head involved, it is quite likely that you'd need to re-animate the hair yourself (or just leave it along, since it doesn't really move in-game much anyways). As well as this, you can probably import the invisible bones and hooks from a normal head (possibly a twi'lek head) and then copy a regular head's way of linking the parts together.
If you do this, you will want to NOT check the "Convert skin to trimesh" box in MDLOps, as that skin piece is what holds the bone-linkage information. The weighting would take some tests to get right, but if you have everything else setup and just have the weighting to take care of, it'll be a lot less stressful...
P.S: I apologize for the assault of information.