1. http://beanfarm.com/index.php?cPath=...0502a805221120

2. I'm not sure what exactly you are asking, but I just used lamp wire from Home Depot. Pretty much anything will do. Just strip the ends off and solder or use the clips (solder lasts longer I've heard).

3. Besides Flexwatt and heat pads all I can think of for a rack is ambient temperature... but then there is no gradient.