I am no pro, but.
. Practice is key, and just from watching pictures it is hard to get shading right lol it is a hard thing if I am honest, because you have to shade according to shape and such. I would say learn how to choose shading colors first and then start shading :0 there is a video called "How to pick nice colors" by MortMort which helped me greatelly on that. Shading will come naturally to you after some practicing. Usually just writing "Pixel art" on google helps me a lot when I look for shading. Even looking at real life things helps me.
As for the head I am saying this from memory so I may be wrong (numberwise) but the first for are Idle, second 4 are grab animation, third set of four is hold animation and last ones (can't remember if 3 or four) are hurt animation.
Good luck!