Fans are usually rated at about 2W without lights, and 3W with lighting. A smaller fan like that is probably closer to 1W. Most fans come with a 3 pin to 4 pin molex adapter, and these can be chained together. http://www.newegg.com/Product/Produc...82E16812189119
Normally I leave one of my power connectors for just fans and plug a few fans into that connector and nothing else. I have had problems in the past with those little fan connectors stop working and causing issues with devices that were also plugged into the same place.
I don't think you'll have to worry too much about a couple of extra fans. For now I would just get the case fans in there and then see what kind of temperatures it is running. I'm not a big fan of those little 40mm fans because they are all loud and annoying. If you can get by without a fan it would be better IMO. I think that heatsink is actually tall enough it should be able to catch some air.