I would replace that front fan, no matter which way its facing, it just sucks
Anyways, the front and back are set to use 80mm fans by default, depth doesn't matter but the dimensions for 80mm fans are usually 80x80x25. Any 80mm fan will fit without mods. If you want to put a 92mm or a 120mm in the front, you will have to mod your case. There is also room to install another 80mm in the back, but you're dealing with the really thick sheet metal, which can get scary if you don't have experience modding cases.
That being said, I have 4 80mm Sunon fans (the ones from NewEgg for $5 a pop) installed to keep my temps where I want em. Front blowing in, back sucking out, and 2 side blowholes (one between pci slots and HD mounting, and one over CPU). The 80mm above the CPU is blowing out, as I have my 8045 sucking air off the heatsink. The one over the PCI is blowing cool air in. I also have a slot cooler in front of my video card and a 5 1/4 bay cooler with 3 40x40mm fans blowing in. Including the 8045 80mm and the 2 80mm fans in my PSU, I have 7 80mm fans in my system. Still quieter than any rig with just 1 60mm 7k screamer, and my case temps are cooler than they were when I had my side panel removed.
Chiz