VRChat Examples/Examples2/Animation/SDK2. Hope it helps
There's a bone hierarchy error with the model that's easily fixable just move the Lower Right leg bones to the Upper Right Leg bone so that they are in a parent/child config.
It's not copyright of you change something about the materials to make it yours. I see custom Ghost models, and color schemes.
Because it would be against the VRChat ToS.
You have to get it from the VRChat site, in which you need a VRC account.