Simple answer to all your questions: However YOU want.
Got an idea? Write it down! The first step to creating a book is getting that great idea and making a commitment to finishing it. Brainstorm. I don't really know what you mean by book structure...sentence structure? Paragraph length...
Is there a website where I can photoshop celebrity faces to create a face of my own? Maybe even add in pictures of my own with those?
Such as...
Taking Hayden Panettier's eyes with
Jessica Simpson's mouth and
Natalie Portman's nose and
My own ears? (optional on my own)
These are just random...