I don't have a whole lot of answers for your questions because some of them I don't know and others are matters of oppinion.

I like the start of what I see and I think you have to ask yourself these very same questions above and make those hard decissions because that's where you are at. What do you want it to look like?

First, general rule of thumb. Do not UV and texture anything until you're happy with the model. Finish the model first.
If this is a test to see what it might look like and to get a better understanding, then be prepared to redo the UV's.

When painting maps it's handy to know how Maya treats black and white. White is opaque, black is transparent. Then you have the whole grey spectrum inbetween to play with. You might want to change to shader from a blinn to a lambert and let the speccularity map, and lights, do the highlights for you.

For instance, the tip of the nose is bright and a little shiny while the side of the nose are more in the shadows.

Keep up the good work.