Moving a water cooled PC is easy, just don't bump it hard or drop it (make sure nothing moves, secure install)... I wouldn't run used parts if it's going to be your first time. A new setup will cost about $400 with a GPU water block and 300 without if you are going with quality parts.
I would go with the Vertex 2 because of the sandforce drivers, but OCZ's tech support is a little iffy. It's pretty much the guy who looks on forums answers the tech support call. I had a big problem trying to put 3 x 30 ocz vertex in Raid0 (non sandforce drivers) and couldn't them to run fast...
To be honest, if you have a 980x.... you should be overclocking. If I had one, I'd spend a stack to cool that down along with my setup. So if your willing to spend about $1750, go ahead and buy it. If your going to run it on air or stock speeds, somehow get your 920 back and drop it in water =P
Uhhh I would recommend getting a thicker radiator, because those gtx 470's are going to boil that water (not really, but it's going to be hot). And you should be fine with 2 gtx 470's for 3D, my buddy is running the same setup.
Uhh if you don't want them to run optimum speed, go ahead. But if you want your sticks to run 1600mhz, it'd be a bad idea because it's a little unstable (depends how your mobo likes it, maybe it won't post)
Modright has pre-sleeved cables, but stupid expensive. Frozencpu has everything but wayy over priced if you can find any other sleeve other than frozen's it'd probably be cheaper
That is pretty cheap, it's almost what I'm building but tons cheaper. And you might get lucky with that i7 920, get a good batch and you can overclock like mad
Sounds a little high, but it shouldn't matter too much if your not gonna max out your CPU 24/7. I don't think paint is super at heat transfer. Instead of Metal > Air, you got Metal > Paint > Air. You got more media to move heat through