awesome! it's more of a fish...building! xD
i think you alluded to this, but i don't see why you'd need to buy in-tank heaters, you could probably just heat the building/room itself.
i'd definitely add plants, something cheap anyways, to the tank... it would be a little extra maintenance, but things like duckweed and water sprite (i'd go more with the former than the latter since it's harder to maintain) can really help with keeping your water parameters steady. also, the fish like it! :'D
i'd also use sponge filters rated for tanks quite a bit larger than the tanks you'll be keeping, they're pretty useful and easy to maintain.