Don't use the undergravel filter or a wet dry filter compartment in the sump. The live rock will give you plenty of biological filtration. The 404 won't be needed either or it can be used for carbon or to add some water movement to the tank along with the 2 802's.
Use an empty sump to hold your heaters, protein skimmer (if you use one)and your return pump. The size of the return pump you will use will depend on the capacity (flow rate) of the overflow(s) you choose.
I'm a LFS geek too.
Where do you work? I worked on 5 different customers tanks today and it was my "day off".