When did Leagues begin? Have the prizes been won?


I believe they started on December 22nd. There's still two weeks before anyone enters the first Champion division and likely three before it fills up and players compete for the main prizes.
Your division is full now but there will be less than 8,000 in Crystal and divisions will slowly fill up as people log on.

Thanks. I think that means Crystal is the highest league anyone can be in. Surprised the league isn't full though. Good luck.

Yes, Crystal is the highest so far. It's almost at 7,000 right now and will slowly increase as players log in for the first time during the week.

Are players paired solely with other players in their respective leagues ?
No. You play in events or random rated standard or 960 games. You're competing within your division, but may never play anyone in it.

Are players paired solely with other players in their respective leagues ?
In addition to your rating increasing with a win, playing your games as normal, you will now be awarded points that affect your standing within your own division. The more you play (and win), the more points you will earn. It's a clever way for the site to have people play more games but I certainly won't be playing this much once the initial prizes have gone.
Good luck