1) Would a 3x240 radiator fit in the Level 10 GT Case.. or stick with the 2x240?
2) Best way to run the water loop? (i.e. Res -> CPU -> Rad -> GPU - Res)
3) How large of tubing to go with?
4) How much coolant would i Need? (i.e. 1 liter?)
1) Looks like a 240 is in there...not sure you can get a 360 without some minor modifcation...is there any room in the bottom? If not, the RX240 or EX240 rad would be a better kit choice than the RS240.
2) Loop order does not matter as long as the pump isn't sucking air.
3) Tubing in the Rasa kits is 7/16"ID, I believe. Check the product site, but I think this is correct. If you want different tubing size, you'll want to replace all fittings in the loop to accommodate it.
4) Just a gallon of normal distilled water and some growth inhibitor like biocide and/or a killcoil. You don't 'need' any coolants, water works best.