For multiple maps vs single maps - that depends on how you're using it. If you're doing a game-res model, the habit I've gotten into is one map for the head, one for the body. I created a tutorial to help my students learn to unwrap in Maya, hopefully you'll find it helpful: - http://methodj.com/maya-uv-unwrapping-tutorial/
I think maya's tools for unwrapping are quite harsh to learn at first but don't get discouraged you'll soon get used to it : it looks more difficult than it actually is. Most people I know (myself included) rely on some external tool or plugin at least to get the basic unfold done. One of the most used is called "Unfold"…