OK, here comes the latest patch.
Again, the model lighting is crooked because the normal maps are for DirectX, not OpenGL. But the main idea should be clear:
No missing Ns'es, no neutral bumps, no FFP, no more fooling around with "I'm an artist, that's how I see it". We've got over half a dozen texture channels, and all of them must be filled with premium quality maps and lit with rich specular lighting. The only worthwhile objective is: minimum polygons, maximum detail.
Note this texture and shader setup still isn't physically based. That's why we're free to use any textures in any slots as is best to produce maximum visible surface detail with minimum possible polygon count.
P.S. Please use the new milder and crisper UV checker map included in the zip, instead of the older one that I copy-pasted directly off the SketchFab screen. It was too acid color-wise and also re-scaled from some arbitrary size.