Welcome aboard Derek. Managing 7 small scale RAS' at 5 locations (4 at 4 high schools) I'm a big fan of DIY small scale RAS.' It's fun yes but can also be stressful.
My systems are quite different than yours, but there are lots of ways to do this, and if you're like me you will make changes as you go.
Here is something out of AES/ Pentairs catalog that should help you with the amount of media material you will need.
URL=http://s11.photobucket.com/user/CecilBaird1/media/bee1ed73-fcc6-48df-b39c-889290c1e47e_zpsnyvopuwl.jpg.html]
[/URL]
Additionally you can get a media from Allied Aqua that is similar to Kaldnes but has more surface area and is cheaper.
http://alliedaqua.com/moving-bed-bio-media-by-the-cubic-foot.htmlIn case I missed it how do you plan on cycling your system: fishless or with some fish? I'm a big believer in fishless myself.
As far as heating your system I use a 1000 watt aquarium heater and controller for my 250 gallon systems because they are economical and do not run continuously.
http://www.ebay.com/itm/1000-Watt-Titanium-Aquarium-Heater-w-Controller-150-400-Gallons-Marine-Fresh-/231482300351?hash=item35e56b97bf:g:fBgAAOSwEeFU4g07
I would recommend insulating your tank with some form of water proof insulation around the outside and most of the top. Something like sheet foam or bubble wrap.
IMHO for best performance I would have your air come up from the center bottom of your mbbr tank. This will cause the media to boil up the center and go down the sides.
I prefer mag drive pumps for their efficiency and low cost. I use this one or a similar one on my 250 gallon systems.
http://www.ebay.com/itm/Danner-Mag-Drive-Supreme-7-700-GPH-Water-Pump-New-/151878870790?hash=item235cafa706:g:OZsAAOSw7hRWP3iw
Prefer a linear air pump for my air supply. Quiet and efficient. A Bluewater model ET60 that produces 60 lpm only uses 40 watts.
http://www.bluewaterpumps.com/air-pumps.php
