Book excerpt: Photographers will find 2,000 information-packed, up-to-date listings of markets open to freelance photographers, including 400 new ones. They will also discover a new index of markets that use digital images, new pay structures for electronic usage, preferred digital formats, more e-mail and web site addresses, plus insider reports and interviews with two-time Pulitzer Prize winner Carol Guzy, William Wegman, and Derek Shapton. Illustrations.