I was going to say something about all those extra fans, and then noticed it was a HAF 912. Yip you need some extra arirflow - those are 80 mm fans,however, and the case will handle 120 mm or 200 mm fans. Larger fans are quieter fans.
You are right, there aren't enough connectors on your board, but you can hook them up directly to your PSU with the 4 pin molex connector - for the fans you selected, the connector is included, but once agian, I would change them for something else. You might even want to get the case in hand before you make the final determination on how many and where to put them. At a minimum, go back and look at the overview/details of the description of your case before you purchase. The overview says it has two fans included, and the details say one, so that is not even clear.
550 watts is adequate for a single GTX460. If you ultimately want to crossfire with two video cards, your motherboard will need to change as well as your PSU.