I've always heard that the biggest sump you can get, get it, because higher water volume is always better. Get one that you can fit all of your hardware in (skimmer*and skimmer pump*, heater, return pump), and make sure that you will be able to get it under your stand. If you already have the tank filled, you can't put the sump in through the top of the stand, so that limits you to what you can get through the doors. Hopefully, you have wider doors than I do - I had a hell of a time getting my sump under my tank.
As for the "ballists", I think you meant baffles? If so, the way most are done is that the first is glued to the sides and bottom of the tank, then the second is raised up an inch and glued to the sides, then the 3rd is done the same as the first. I believe this helps with some bubbles? Water flows over, then under, then over and out the other side to your return pump, or refugium(refugium would have the same 3 baffles on the other side, which would then go to the return pump).
Just remember, bigger is better. I think mine is around 15-20gallons for my 75g tank - bigger would be better here.
Hope that helps some.. I'm sure others can add some better details. so BUMP