Yes, I have extensive experience with the 3D mercury case. I Changed the radiator to a Copper/brass style for corrosion protection, not to say theirs isn't worthy, just preferewnces. The fan on their Rad are fierce and can well be heard on high. Modifying the pump mount would be another easy trick, just space the tank up about a nuts worth and mount anti vibration below the pump otherwise it's very noisy. I have a 2 120mm Radiator attached to the back end blown by the two 120mm internal fans. Also, I have a triple Rad attached to the other side of case parallel the ground at an angle. I have pictures. All in all thisn is the most workable future proof case I have seen or built. With modifying capabilities beyond. To answer the rest of your questions: 3/8" Tubing(x 5/8") is plenty big using bitspower compression fittings, Back Ice GTX Rads work fine, Air is good for the top has own intake for rad and if using the mesh(recommended) it allows for more air flow. The sound level if modifying like mentioned is very low but then I have mCubed looking after that, controlling everything.