I used a different 3D model of a skull that looks a bit different. The oil clay I am using is more granular and too sticky than chavant NSP (a bit expensive) From the beginning I've wrapped the neck with too much paper, so made it too large.

You can dissolve it in some kind of alcohol and then spray it with your finger and a cut brush. Or dap with a sponge. Or make small holes with a needle (Slant and than ligt) and brush in some dissolved Chua ant with a brush.

I’m gearing up to oil paint down the road. Well, that in and of itself is super complex, as beginning attempts have shown. I am now getting down to basics, lots of drawing to be done, skills to learn, a gargantuan need to learn anatomy, and then mixing paint will come later, so that when I actually use canvas and paints, I can create something of value and not some monstrosity to be found in a thrift store or trash bin.  I’m wondering what is advice of practicing digitally versus real pen, and paper, pencil or charcoal in developing skills? Any thoughts?

It can be sanded but you have to be careful because the silica dust is out good to breath in. It is difficult once the sculpture is completely dry to make modifications like adding clay to the surface.

Oh where do I start!! Hair, that damn pesky thing. Sculpting different emotions. Eye depth in the face, I struggle with that one! subtle mouth expressions. Oh, just everything!

Sometimes heating a knife and tapping the sculpture with the flat of the blade so that it melts the surface and then pulling it away can create some interesting texture. You can also just use a rough rake to create some short strokes in multiple directions that go along with the direction of the stubble. The difference in texture from the smooth skin to a rough tooled texture might be enough to give the feeling of stubble.

I dont understand the question

Well she worked out kinda OK. Here I was worried about the ear but it was the shoulder that blew! So I glued it and added some gold paint.