Dave,
A 7lb brisket probably doesn't require a full ring of coals. Since I'm new to smoking, I didn't know whether the smoke would take 7 hrs or closer to 10 (1.5 hrs/lb). I had quite a few coals left when I took off the brisket, so I'm sure you can get away with less coals. I'd rather have too many than have to add later.
I did not foil at all during the cook. I only checked the meat at the 7 hour mark. It's at that point that I also discovered that all of the water in the pan had evaporated (I probably should have filled it a little more at the beginning).
I didn't use a thermometer to check the meat temp. I cut into it and found perfection so I took it off and let it rest. On a thicker piece of meat, like a pork butt, I'd probably be better served to use an internal thermometer. I used a basic Taylor candy thermometer in the top vent to measure the smoker temp.
As I cut into the brisket, I found a perfect 1/8 inch smoke ring around it!