Id suggest having a chat to [link] She is really lovely and has been approached about a few of her artworks being used on things like books and educational booklets and CD's. She would most likely be able to answer your questions in a practical sense As far as I know the guidelines for how the art can be used can change a lot depending on the buyer and what they want/need.
Graphic Artist's Guild Handbook of Pricing and Ethical Guidlines. This book is extremely helpful with these things. It tells you how to go about all of the stuff you have questions about. It have examples of invoices and contracts.