i have a question before giving the actual feedback on this marvelous thing.
is it 100% custom model, or a T-posed model with custom touches?
ok, the first thing i noticed is the belly, it's not symetric, this could be because of being a pre-posed model, in which case it would be understandable, but yet fixable with some UV tweeks or even model tweeks
another thing, and this is a pure model issue, is that the mouth isnt one piece, and that's not the problem, the problem is that it's noticeable, check this:
on the texture side, there is some stretching at the arm that could be or probably should be fixed:
another texture issue would be the dismatch at the belly's bottom with the leg area, and some stretching between the legs:
now on a more opinion like area, i believe the tongue is a bit too detailed, but as i said, that's just an opinion.
conclusion:
i believe this model is a T-posed trophy model, not sure though, if so, it would explain some of the issues noted above, and recounting, ive only found 2 model issues all around, and 2 texture/UV issues.
finding only 4 problems in a "custom" or "fixed" model is very nice, haven't looked at the rig yet, and i dont think i'll try to give feedback on that, i hope this helps both you and dot improve your future hacks, you're both genius and im totally LOVING the texture work