Hrmm well, I'm not sure about the avatar shadows.

I think Nad here can help you with that.

*me hands question to Nadnerb*
And about the alpha vertex-paint. What in particular do you need to know more about? It was really just trial-and-error for me. The most important thing to know is that the second vertex-paint layer is alpha--white is solid and black is alpha and everything in-between. The rest of it is easy to learn from just google-ing and playing about with the buttons in blender.

Currently getting some ink on my hands over at the Guild Of Ink-Makers (PyPRP2).