I can only answer a couple of your questions,
1- Yes, I only use the clay bars for maybe 4-5 times, you dont want to re-use it after it falls on the ground or has big pieces of dirt on it. Allways keep it lubed and store it moist on a zip-lock baggie.
4- Buffing machine is not really necessary but it'll make it look 1million X better, plus it will save you from having a sore arm, try getting a PorterCable, in the long run they are a good investment
In the past I have used only Einzett producsts, Poor Boy's, and Vanilla Moose (1Z I think this is the greatest product lineup) [ Apparently this place is the only internet seller for 1Z products-->
http://www.fusionperf.com/subcategory.asp?fusion=7 ]
Good luck and post pics after you are done.