Answers
Do you plan out the whole book before you write it?

Yes, I have to because my day job means I can't keep it all in my head. I need it all on paper so I can pick up where I left off at any time. I start with a synopsis, then I plan all the character biogs so I know, not just what they look like so their hair doesn't change colour mid-draft, but what motivates them, what and who they care about, what their dreams and fears are. Usually they start to do their own thing by chapter three but the thought's there! Then I plan the story outline and finally the chapter breakdown. I won't necessarily stick to it – with SSG I had to cut a whole story thread because I was 80,000 words in and if I stuck to my original plan it would have taken 200,000 words to finish - but it's good to have as a guide.