By the way, last August and September, my literary agency BookEnds did a three-part series called "Contracts 101." Jessica Faust had some worthwhile things to say about advances and delivering a manuscript.
The first of the series is here. You can find the other two by entering "Contracts 101" into the search engine of the blog.
At about the same time, agent Kristin Nelson did a ten-part series on what a sample agent's contract looks like.
Go here to start the series.