I have a feeling that this is going to be a book a lot like Street Gang just focusing on Jim instead of Sesame Street. If you have followed the authors blog you will know he did a lot and I do mean a lot of research interviews and other things to make sure he got the whole story of Jim's life.
Street Gang tended to provide paragraphs and even pages of biographical information on nearly everybody mentioned, regardless of how important or associated with the show they are (though there are people who are very important to the show who were mentioned who didn't get much biographical information... It seems biographical info on Jerry Nelson was small compared to others, and Roscoe Orman was only briefly mentioned, though an unpublished section on him was at the official website). I hope this biography doesn't do that too much. I don't mind if it gives a little history on Jim's family and the key people he's worked with (Frank Oz, Jerry Nelson, Don Shalin, and so on).