To answer #3: Rubbing your hands helps to stabilize your dream. I've found that it works 99% of the time--the problem is remembering to do it. Whenever I can remember to, I always rub my hands together and really focus on the feeling of the friction, what my hands look like, my surroundings, etc. to cement myself into my dream while remaining lucid. Doing so periodically helps to keep it stabilized and prolong the dream. From my experience, I've been able to actually "prevent" waking up, even if only for a few minutes. Whenever I feel myself about to wake up, I look at my hands and rub them together and I can usually get a few minutes to remain lucid and have fun and a few minutes does seem like hours in a LD. At least in mine.

As for the difference between semi-lucid and all-out lucid, I believe it lies in what you are able to do. A semi-lucid would just being aware that you are dreaming but lacking the power to actively change your dream world. An all-out lucid would be knowledge that you are dreaming (of course) and the ability to change the world around you based on expectations (as Puffin said). However I don't know if that's the correct definitions of the terms; Puffin will be able to provide better ones I'm sure. Edit: Puffin ninja'd me.