Yes, you would win $57.
However, my advice to someone else on the Contador subject is the following:
The good thing about Contador being so short is that his odds won't come in that much. Yes, he will probably do the prologue well and be close to the lead, but his odds will stay roughly the same.
Due to this fact and the fact that the first few stages are sprinter friendly, wait till after the cobbles. If he does lose time on the cobbles, his odds will go out and you can get on him there at a better price.
If he doesn't lose time on the cobbles, then his price should stay around what it is now or maybe go in a bit but not much.
The way the betting works is as follows:
If a rider crashes during the race, you will lose your money. If he abandons or gets done for doping during the race, you will lose your money.
If he gets caught after the race, when he has been awarded the win, you keep your money. Same thing for stage wins.
I.E if you had Ricco to win the stage he won, you would have been paid out. He got busted for doping after the stage win, the books couldn't take your money away.
I.E if you had Ricco to win the Tour de France outright and he got busted for doping during the three weeks before the race was finished then it's tough luck, you lost your money.
I.E if you had Landis to win the 2006 Tour de France, you would keep your money.
To answer your other question, if you haven't picked up the answer above. You can bet the winner after the race has begun. For example, they had the outright winner in the Giro open to the last day. Obviously before Basso took pink, he was $1.55. When he took pink, he was $1.01. At one stage, Basso was about $8 to win. Hence why I mentioned about Contador. If he loses time on the cobbles, his price will drift out depending on how much he lost. So really, if you want to risk the value on Contador, wait till later in the first week.
I made a killing last year in the sprint stages backing Cavendish for the win and Farrar for the place. Cav for the win was around $2, and then went into $1.80, $1.60, $1.50, and even $1.40 on the Champs last year. Farrar's price for the place stayed around $4-$5 for the first few times. It wasn't until the bookies picked up the fact that people were making a killing that they had Farrar's odds something like. $8 to win and $1.80 for the place.
I intend on doing the same thing this year on sprinter friendly stages. Back Farrar for the place and potentially Cav for the win. Really, I can't see anyone in the flat stages coming first and second other than Cavendish and Farrar.