It'll fit for sure, but you'll want to put them in slots 2 and 4 to give them more room to breathe.
I also do something a little unorthodox in builds like this where there's a lot of heat stemming from the bottom and exhausting into the case. I'd reverse the rear exhaust and top exhaust to be intakes. This blows the air down and away from the CPU as your CPU will not exhaust anywhere near as much heat as your GPUs do. Then once you've done that, take the front intakes and put them so they are now exhausts. This should pull that air being pushed back down out of the front of the case and help keep things cooler.
In terms of fans, you'll want a high RPM for the front, anything really will work as long as it's RPM is above 2000 and has...