Your temp swings sound fairly normal for your first smoke in the #3 with 7 lbs of meat. The swings will probably get a little smaller once you get more seasoning built up. Mine did. If your brisket was 7 lbs, sounds like (and looks like) mostly flat, with maybe a teeny bit of point attached. A full packer brisket (both point and flat) will vary, but are generally in the 12-16 lb range. I've noticed that when grocery stores sell flats, they over-trim them. You want about 1/4 inch fat cap. If yours was over-trimmed, could have contributed to a less moist end-product. Did you use a foil pan next to the firebox with water/liquid? 12 hours sounds a little long, but not outrageous. I have pretty good luck with 225 for brisket. I take my briskets to about 195. Do you know what grade your meat was? A USDA Select brisket flat is going to be more dense, with less fat, and probably take longer to cook than Choice or Prime. Also, no need to let the brisket sit at room temp. It can go directly from the fridge to smoker. Cold meat takes smoke better. Sounds like you're off to a great start though! You've got a lot of the concepts down for never having smoked before. You'll be a pro in no time! Your neighbor has no idea how easy making great Q is in the SI!