For a CPU loop, take a look at the XSPC Rasa kits (I wouldn't necessarily start with those because of the pump, but there are variations out there that use better pumps).
If you want to throw your GPU in, you'll need to make sure you have the appropriate amount of radiator space to dissipate the right amount of heat. Keep in mind that faster fans will dissipate more heat than slower fans when used on the same rad, so if you'd prefer quieter fans you'll need to compensate with more rad space.
RAM coolers are quite useless (are we talking fans or waterblocks?) IMHO - DDR3 produces so little heat that it's really just a waste of time and money. If you're doing it for looks then so be it, but it really is just for looks.
erm... well you need to decide on that fact, apparently the answer is staring up your nose
How much am i looking at for a simple CPU loop?
$150 but the pump will be compromised. 300 if you're going to want to add more raddage and some blocks for the mobo and gpu's in the future without worrying about flow rate/pressure.
And if i want to add a GPU into the mix?
$400+/- depending on going with unversal blocks or full cover blocks. If you change GPU's often, stick with Uni's and if your fine with that one 570 and won't hange it for another 2 years, get a full cover. I like FC's basically cos they look sleek.
What case do i use?
up to you, you can fit just about anything with case modding and well, maybe hang the rad off the back of case or up top above the case.
i like the look of the NXTZ Phantom will it do?
google some images with the case+watercooling...i think theres a club for that case in overclock.net see how they've done with watercooling their rigs and if you like what they've done - maybe add your own twist to it.
Will i need Mobo coolers on my Asrock Extreme4?
mobo's don't give off much heat, but you can add blocks to them only cos of aesthetics - you're actually better off having a 120mm fan blowing towards mosfets/vrms on mobo
Are the RAM coolers useful?
ram don't produce much heat now that they're avialable @ 1.35V and the highest now being 1.65V. The dimms i have run cool to the touch at 1.65V 1800MHz
And Really could i get away with a H80 and alot of fans?
temps will go bad and you'll want to add fans to that mixture? this is more noise - they did have good results with Noctua NF P-12's but then again, with that kind of money - get a kit and build your loop.