1: Is forgetting the world necessary?
It's best to forget about the "outside" world and focus your attention on the dream world. Usually thinking about your body laying in bed or any externa, reality has a tendency to make you wake up.

2: Do eyes count for SP?
Well, SP occurs during REM sleep, and REM stands for Rapid Eye Movement, because the eyes are flicking around really fast the entire time. So you can still move your eyes while the rest of your body is paralyzed.

3: What happens if you focus on your body in a dream?
Sometimes you do become aware of your sleeping body when you're in a dream, and its usually just before you wake up. Best to concentrate on the dream itself.

4: How to escape SP?
This one I don't really know. I leave it to others to answer it, plus I'm sure some people can give better/more complete answers to what I've answered. (Or even just tell me I'm totally wrong )