http://www.chess.com/members/view/latnox
I created it just to participate in tournament, so it's quite empty :)
I think, that 10 minutes per player should be sufficient. Blitz are good if you can play well, but since some people are beginners they will start to losing by time. About this cheating, I think that best solution is to just invite players, that you know of fair-play.
Any specific date, when tournament will take place ?