Put 20 cyclists in a room and you'll get 20 different opinions on chain wear, maintenance, etc. So this thread won't be coming to any sort of definitive conclusion.
I tend to get ~2500 miles out of a chain. I clean it on-the-bike once a week (~150 miles or so), re-lube it, and that's about it. I have one of those Park Tool "chain checkers", but I find that they indicate that the chain is "worn out"
long before my trusty ruler indicates that the chain has stretched 1/16". (One link is exactly one inch, so on a brand-new chain, one foot should be exactly 12 links).
To clean it, I just spray some degreaser on a rag and scrub away. Seems to get it reasonably clean. I've used other chain cleaning methods, and no matter what I do, within 50 miles, it's looking like I never touched it.
All kinds of good info is here:
http://sheldonbrown.com/chains.html