It will only be accessible from the back which is my laundry/fish room, so it's not that big of a deal. I do have to stand on a step ladder though to reach inside of the tank. I will probably end up falling in it one of these days.
Yes, the return will be in the middle of the sump. The drains will come down on the right and left, but there will be a ball valve on the right, and it will be connected to the drain on the left. Any excess water will drain into the skimmer side. (That's a horrible description, so I'll have to post pics once I do it. I think a couple of other people on here have the same design). If that works ok, I may put a dsb/chaeto on the right hand side. If it doesn't work out, I'll just do rubble.
This is going to be a FOWLR tank. I've got my little sps tank upstairs, so I wanted to try some aggressive fish. Maybe in the next house I'll do a bigger coral tank.