The odd is registered when we bet or when the bet is closed ? Because if the odd displayed is higher when we bet than in the closure we can lose money.
It is impossible to lose money if you win the bet. The odds change because other people bet against you as it says on the page:
Bet on the latest events against other FreeBitco.in users and win a share of the prize pool if you pick the winner!
Obviously you don't know what will be in the prize pool to be shared by the winners until all bets have been placed.
All other bet sporting website are "what you see is what you get".
No. Those that offer fixed odds betting and bet against you will tell you the odds when you place a bet but in player versus player betting that isn't how it works.
https://en.wikipedia.org/wiki/Parimutuel_betting