40G Breeder Build

[centex99]

So am deciding to get back into the game and build a 40G breeder setup. My previous tank was a 14G BC. I was considering other options, but for the price, I think I want to go this route ($1 petco sale).
So my current decisions I need to make are what size sump to build for it... Options: 20H, 20L, and 29G... the 20L/29G having the same footprint, but taking up most of the stand's interior foot print, or the 20H being 6" less in length (same height as 29G). I'm thinking of having the pump and skimmer in the sump and having at minimum an ATO and maybe 1 reactor (gfo/carbon likely).
Second question, what kind of flow should I setup for this tank? I'm likely going to keep softies and maybe some LPS. This obviously dictates pump decisions.
Any suggestions on some overflows? I'm going to run either a hermie or bean setup and a single return. I'm thinking an overflow in the center and return on one of the corners (or maybe split it and goto both corners).
Any suggestions and tips from experience on these decisions would be greatly appreciated. 

 

I plan to go buy the tank and sump tank today while the $1 sale ends today.  Also if someone in south Austin could help me with drilling that would be great.  I also plan to buy another 20G (regular or long, not sure yet) for a QT tank.  I plan to QT after doing tank swap method in 5G containers/buckets...