I'm just getting interested in lucid dreaming, and plan on trying to do it soon. I have some questions.

1.How long does it take to start lucid dreaming? I already know about the dream journal, and I'm going to start it next time I dream.

2.Will writing down past dreams in a dream journal work, or is it too late? (My most memorable dream happened when I was six)

3.Can it be dangerous? Like, could I be mentally injured, or even physically?

4.What is sleep paralysis?

5.Is it like being in real life, except where you have control over everything (almost), kind of like the matrix?

6.What is the dream world like? Will I see places I go to everyday, or be in a big blank room, or even a city? Will I see my friends?

Those are all the questions I have. I'm very excited too begin Lucid Dreaming.