Since we now customize these parts by just choosing from presets, I assumed they were based on pre-modeled meshes. Couldn't find anything while browsing the BSAs though. Do you think it'll be possible to do more in-depth editing on these in the CK, and save our own custom presets?

I sure hope so. That would be awesome knowing what this community is capable of.

There's a folder under textures called "Facemods" which has a lot face textures for different shapes. It's like the texture alters the shape of the mesh slightly.