EXCLUSIVE: The definitive book on talent agency CAA is being written by James Andrew Miller, the same author who penned the bestselling Those Guys Have All The Fun: Inside The World Of ESPN and the as-yet untitled CAA book will be the launch title of Custom House, a new boutique label under William Morrow/Harper Collins. The book will cover decades of the talent agency’s history, from its beginnings when ‘the boys’ — as they were called by their agent mentor Phil Weltman…