Sorry, did not understand that. What is 1%?
Also, do I need at least 0.00001000 BTC to be eligible to "Multiply bonus account"? Because I have more than that and can't find the option to bonus account...
It means that the amount of bonus you are eligible for is 1% of the amount you have wagered since the last bonus you took. So if you place 1 BTC in bets you would be eligible to claim a 0.01 BTC bonus. It will not show any bonus available until you get to the minimum of 0.00001000 BTC by wagering 0.00100000 BTC.
Last question (promise, won't keep bothering): sometimes I see "free" on the Roll History, what is that?
That means it was a free-roll from the faucet, ie. when you roll from the FREE BTC page. You're not bothering, you're a pleasant change from the trolls I usually have to deal with.
