Cleaning and sanitizing is pretty quick and easy. See http://www.bodensatz.com/staticpages/index.php?page=Soda-Kegs-Maint as well as the sticky threads in the bottling/kegging forum.
Takes about an hour, most of it just wait time. Just don't let things gunk up or grow after the keg is finished with the last serving and you should be fine.
As for cooling. I'm looking at options there too. It seems that the method I'm looking to use is to use a fair sized mini fridge though some people have talked about certain types of heat exchangers to cool the liquid as it goes through the tubes, but I don't remember how much that costs.
Oh, and as for sanitizer, I hear starsan works great and since it lasts, just have extra kegs on hand so you can transfer the sanitizer from one keg to the other, and just let the sanitizer sit in the cleaned second keg for a while.