Non-fiction is a book with factual information. Some books, such as comic books or poetry are classified as non-fiction regardless.
No. Realistic fiction indicates that the book is something that COULD happen, not that did happen. If there aren't talking animals or magic spells in it, for example, and it's a story about a kid...
Unless you've seen any vampires stalking around lately, no.
Fiction is stories invented by the author. i.e it is not true. Non-fiction is based on facts and is true.