That thermal paste is good, it's what I use
Never seen those fans, fan choice depends on the rad (see below)
Most cpu blocks will give similar temps, get the one you like the look of!
If you're cramped for room in the case, a bay res is good, the one in the kit I linked houses the pump as well (hence using 2 slots). Again down to your personal preference.
Pump is good, you might be able to get one cheaper just a different brand.
Just get some distilled water from the hardware store and use a silver coil.
That rad is 20fpi (fins per inch), the more fpi the more powerful fans you need, you should get a fan controller whatever rad you go with, depends on how quiet you want things.
I'd also use compression fittings over barbs, safer and look much better.
Whatever you do, when you first put it in the case, cover all your components with towels and tissues and run the loop for 24 hours to check for leaks, cross your fingers and hope you don't fry your comp!
