I belive the bulb that this fixture comes with and the one thats avaiable from Grainger for replacment is to low of kelvin. The bulb appears to only be a 4000 kelvin lamp.
I would suggest a higher kelvin lamp. Depending on the bulb connector and the ballast type you may or may not be able to use other MH
lamps in the unit.
Other than the look of the powerheads in the tank I dont see an issue with 5 of them bing in there. What size are the PH
's? On my 75 I have two Hagen 802 powerheads that alternate every 10 minutes.
Detrius can collect on the bioballs if you dont have a trickle filter pad before them to collect the big stuff. If your not running a DSB
the bioballs can cause a steady increase in your nitrates as the bio ball area is highly oxygenated and thus a perfect place for nitrification to occur. Using live rock rubble that is fully submerged in the wet/dry will do the same thing as the bio balls and the nitrate production will be lower. The water level in the sump will need to be a little higher than with bio ball operation.
The tang should be fed a steady dite of seaweed with the occasional meaty meal. What I use is dried nori that I purchased from an online health food sthop. If you have a god asian section in your grocery store you might be able to find the same thing there. Its basicly the stuff suchi is rolled in. The meaty foods can be ground up fish, shrimp, squid, clams, etc.