What is the maximum amount any faucet offers to claim one time ?

well if you are like i think even something around 0.4, but don't bet on that too much

usually they are worthless, unless you do some cheats via bot

Freebitco.in gives 200$ as max profit

$200 i never see there that amount won by any user, much hard to hit that.

Do you know all the users on the site?