Hey Mc-fleury

Looks good, so I will answer the questions you have asked: When creating maps ie:bump color etc they will not distort as such as its the geometry thats moving and not the uvs, so providing those are good all will be fine.
As for the expression for more anger pull faces in the mirror to see how things move, I do this all the time for character blends, so seeing this and your question it stuck out a mile and that was that the top lip needs to be raised more over the teeth so the gums are exposed as with the lower but not as much, though the lower lip curls slightly outwards when it reveals the lower teeth in this manner.

Ive also attached Kong himself for probably a better example
Hope this helps
Jay