for your first time soil is much easier, reliable, harder to fuck up (though not impossible) and has the added benefit of being much cheaper to startup, this leaves money for things like lights and ventilation.
i harvested 2 and 1/2 oz off one plant in organic soil.
and if i understand you...you wanna use the water cooler for the dwc AND as the grow space?
i dont think it'll be big enough....
if you can be a little more descript i'm sure you'll get more replies, mabye some pics?