To the jackpot system..does it calculate with miner's power? Something like each share is lotto ticket? When one miner=one lotto ticket, I can run 10 miners on one GPU to have bigger chance to win

Not going to do that, but maybe set you up as my backup with few mhashes if it works this way
You have a good point, but we don't want to punish the cpu or low mhash miners...
So for now active mining on your account = 1 lotto ticket.
My guess is that with 500 or more accounts, it's not going to matter that much if someone creates a few accounts... We'll see what happens.