Most of the type of information you're looking for is in the primary literature, so you'd need to search for specific journal articles on the topics you're interested in. I wrote a summary on some aspects of chameleon color change a number of years ago (
http://www.chameleonnews.com/04NovAndersonColor.html) but there is a lot more information now about color change and behavior in chameleons in papers by Devi Stuart-Fox. As for other chameleon physiology stuff, it depends on what you're looking for (feeding and locomotor biomechanics, muscle physiology, metabolic pathway-type physiology, etc.). Some of my feeding biomechanics and muscle physiology work can be found on my website:
http://www.chamaeleonidae.com/Publications.html
Chris