Does Book Module create brand new node if other nodes are included in a book?

I am running the latest version of Drupal 6.x. for a home remodeling site. There are over 500 articles aka story nodes on various topics. Have never enabled the Book Module permission until now. When I create a new node or edit an older node, I notice a feature that allows me to make the node a part of a new book or an existing book. Thought this would be a great way to organize content and encourage others to help write and edit chapters.

So here are my questions:

1) Does the book module actually create a brand new book node or is there really a story node just being used in the book outline? In other words if I have a total of 500 story nodes and I do the above will I have 1,000 nodes (story and book nodes)?
2) Theoretically, if I chose to make all of my story nodes as part of a book or books, what would the impacts be on performance and the database?
3) Does anyone know of other drupal sites that really use the books module besides drupal.org?

If this is not the right place to post this I apologize. Thanks.