Z77 is LGA 1155, I believe the LGA 1150 enthusiast boards are going to be Z87. Why do you want to pull hot air into your case? If you put the radiator in the front of your case and pull air through it, that hot air is going straight to your GPU. Sure, you've got an H100 ready to cool the GPU and CPU in one loop (or two, but I think two closed loops plus a case will exceed your 20 lbs) but you want the hot air exhausted from your case (top or back, top works well for most) not pushed toward your electronics. Unless by pull configuration you mean that you want to pull air from your case and exhaust it out the front, but that's technically a push.
GPU: Do you need 2? Do you want to wait until Q4 and get the new stuff? Any idea if another GK110 card will come out 1H this year? (there's a scaled down titan coming out sometime, not exactly sure when, has slightly lower memory bandwidth and 5 GB instead of 6 GB of ram, same clocks, same GK110 architecture, not sure what else has been disabled)
Remember one key thing for the SLI thing. You want a reference designed pair of cards if you do go with SLI because of exactly what you mentioned. Case temps. If you get some TwinFrozr or some such pair of cards, they are designed to run by themselves. Yes, they have the capability to SLI, but when you put 2 of them next to each other, they exhaust their heat all over each other. You want cards that suck in cool air from the case and exhaust it out the back. Many people are disappointed by SLI/CF temps because they buy these non reference cooler models and get their boxes really hot. Reference design doesn't mean you can't get one of the special edition factory OC versions. You can find those with reference coolers as well. The GTX 680 Superclocked+ is a good example of a factory OC card with a reference design.
So, light weight, water cooled, Haswell, enthusiast board. It'll be a stretch to get this thing under 2k, but I believe it may be doable. Just remember that the i7 and the Z77 board is going to be a large chunk of that budget right there, so you might not have enough money in that budget for a pair of powerful cards in SLI. 330 for a CPU, and depending on what mobo you go with your Z87 might end up running you close to another 300. H100 is another 110, hard drive is under 100.
I noticed you mentioned quad channel RAM. You understand that the Haswell i7 isn't going to be able to address RAM on 4 channels, right? Dual channel is the max, just like with ivy and sandy bridge i7. LGA 1150/1155/1156 only has so many pipes to shuffle data back and forth on. You have to get the LGA 2011 (or whatever pin configuration the Haswell generation of X priocessor is going to be) CPU and board to support quad channel RAM.
As far as your ancillary stuff like what brand for cooler and PSU, that's completely up to you, you'd have to see who has the biggest rebates at the time out of the brands you trust. Also, the frame lag from crossfire happens in SLI as well, it varies from game to game, and system to system, but neither manufacturer is immune to it, so if you're jumping from team red to team green just because of an experience with some microstutter/frame lag, you may find yourself disappointed in the future (or you may not, it varies.)