Yes, you read it right! That's one item up for sale at the Ebay Philippines website. :)
No, this is not a discussion of the "what came first - the chicken or the egg?" kind.
Yes, many books have been made into films. Some books are difficult to translate into the screen; just ask Stephen King how he feels about his books being made into films. Some books like those of Michael Crichton and John Grisham are so cinematic, scriptwriters can do them with their eyes close. These are the books on which the films are based.
Yes, many films, specially the top grossing ones, were also novelized after they were shown in cinemas and their DVD and VHS versions are put on sale. These books were written based on the films.