A few suggestions -
Ditch the bioballs, just use rubble live rock, you'll be better off with that as the bioballs tend to trap debris.
I run my skimmer in the first chamber, that way all of your bubble making stuff is in there so there's more time to offgas the bubbles so your return pump doesn't pump them up into the main display tank.
As for sizes, for your skimmer chamber make it however big you need it to be to fit the skimmer in there and your overflows or whatever else will be in that chamber. No need for it to be any larger than it has to be.
For the return section - this is the one that matters. The chamber where your return pump will be is where your evaporation will be evident, so unless you're using an ATO to keep the water level fixed, make this chamber as large as you can to accommodate evaporation without letting the water level get so low that the pump sucks in air.
In the DC Metro Area? Check out GWAPA