thanks guys.
ive never had a problem with one of those true union check valves. thanks for jinxing me Barry ! Im going to have a ball valve to close it off during maintainance but the check should work fine. I didnt like the look of decreasing the overflow to add a return plus it would decrease surface skimming.
as for the A/C, there isnt much I could do unless I wanted to stick the tank in a corner or back bedroom. Atleast the tank wont need a chiller or fans.