I learned a little bit about the bonus situation at Card Room.
After you deposit you need to go to live support to ask for your bonus.
This is what Carlo had to say about the bonus conversion.
"The 110% Promo Bucks promotion is credited up to a maximum amount of 500. It is credited to a separate balance known as promo bucks. It consists on while you play at the tables and contribute to rake, a percentage goes back to your account. The exact percentage is 50%. Once this rake rebate accumulates to $5 then it automatically converts to your real money balance in that same increment.
Basically, what this means is that per every $10 you have accumulated in rake at our real money tables the system will automatically grab 5 PokerBucks and convert them into $5. These $5 will be instantly credited to your real money account free of restrictions."
I hope this was helpful!