First off, don't go by time, go by internal temp. There's alot of methods and recipes posted here already on this subject, so do a search and choose your own weapon.
As far as the filling up the box with charcoal, no. Do this:
If you have not modded your CG with a baffle to help with the hot spot at the sfb end, then flip your charcoal grate upside down in the smoking chamber, setting it just above the sfb opening. This will help stablize the temps across the grates.
Get a charcoal chimney lighter, fill it with lump charcoal and dump that (unlit) into the sfb. Then, light a chimney full of lump charcoal, and dump that on top of the unlit.
Place two or three chunks of your favorite wood around the pile, let the coals develope and let the smoke settle down, then install the bird on the grates.
Everyone has their own chamber temp recommendations... I like 300-ish. I won't go into alot of detail here, this should get you started and don't forget to do a search on the different turkey methods everyone is using.
Good luck and have fun!