I would look at running both the sumps on a tank that size and look at probably 2000w of heaters, 4 x 500w would be good, 2 in the tank and 1 in each sump.
Make a massive wet dry out of both the sump tanks, cram it full of pot scrubbers, either that or you are looking at 2 x Fluval FX5's for a tank that size.
Fish, you are actually limited believe it or not on some of the big species, simple reason the tank is not very wide, 24" is not a lot of room for a 20" fish to be able to turn around in.
I would HIGHLY RECOMMEND, you place a piece of 1" thick styrofoam sheet under that tank before it goes on the stand. A tank that size, the water pressure on the sides is immense and it MUST be ABSOLUTELY LEVEL, 1-2mm off can easily cause the seam to give way. Have you had a structural engineer check the area you are going to put the tank? You are looking at nearly 4000lbs of water weight alone and if you want to keep cichlids, add another probably 200-300lbs if not more of rocks to make them happy.
I would love to see a picture of that tank, you can add pictures, by clicking "go advanced" in the message window, on the top of the box which will appear, there is a "smiley face" next to that is a paper clip, you can use that to attach pictures. If you have the pictures stored on something like photobucket, you can use the insert link option (green under the smiley face), use the direct link to the picture.
Welcome to the forum and am looking forward to seeing this tank come into reality.