1. A dream journal helps you develope dream recall, you should write down about 2-3 dreams a night until you progress to ATTAINING lucidity.
Through a dream journal, you can find dream signs, and reoccuring dreams, to help you gain lucidity.

2. It depends on the person, i suppose once you can gain lucidity normaly, it will happen alot. Hope it does for ya!

Check out the TUTORIALS forum, it shall help.