Is this how everthing is supposed to be hooked up? I am still not sure about the other drain coming out of the overflow? Does it come together with the other drain with pipes and then run to the top of the sump?
The picture there looks like the tank doesn't have any top or bottom restraints. Meaning the whole thing is held together by the silicon seals. I'd take a VERY close look at those seals before putting the tank in your house.
Most people seem to have no problem with them. Personally I'm still finding bits of sand in corners of my living room after my 75 exploded on me.
I think the chiller return goes to the far right where you wrote overflow. You don't want the cooled water going into the same section that's drawing the warmer water to the chiller. The bigger hole on the top left of the sump where you have the chiller return is probably for the 2nd overflow from the tank.