HI Crobe. I have the Q500 case, and I just watercooled mine, so lemme help. It is a big case, but surprisingly hard to fit things in..
You could mount a rad over the PSU, but space is very limited. Some of the black ice rads will fit, but double check the width. You could mount it to the top panel, but it must be just under 6" wide, so you probably aren't going to use a regular cheap heater core. (the rails that the top panel sits on get in the way...) There's also the bottom front of the case, but the HDs interfere. It just depends on the size of your rad.
I took everything apart and went crazy w/ a jigsaw. I moved the PSU and the HDs, and cut a huge hole in the metal at the bottom front of the case. I found a cardboard box that fit my rad, and installed the rad on one side and the fan on the other... then I set the whole unit in the case. The pump occupies 2 CDROM bays. The eheim 1250 is quite large, so that's the only place I could put it. Dunno about the ViaAqua. Silicon hose sux... it's porous and allow some of the coolant to evaporate through. No leaks, but you can smell the water wetter. Tygon is better.
Fan: get a 120mm L1A panaflo or papst or some other quiet fan. I have a 172mm comair and it's noisy. I'm going to take all of my cooling stuff out and put it in a separate enclosure. You may not want to do that. ..yet.
