I also intended to summarize the history of the CIDG program but found that the Army publication detailing the history of SF in Vietnam did such a great job of explaining the program from its humble beginnings organizing specific mountain tribes (Montagnards) to prevent communist control of the border areas until the early 70s when most border camps were converted to the Border Ranger program. The publication can be assessed at the URL below.
http://www.history.army.mil/books/Vietnam/90-23/90-23C.htm

Vietnam Studies
U.S. Army Special Forces
1961-1971

CMH Publication 90-23
Department of the Army
Washington, D.C. 1989 (First Printed, 1973)