Although it will take the longest to cook, whole packer briskets are best, untrimmed. Try to keep your pit temps <220, I shoot for <215 so as never to "boil" any moisture out of the meat.
Fat Cap Down, at least thru the majority of the cook. You can start for the first couple hours with it up to jump start the bark if you like but the rest of the cook it should be down to help protect the fragile flat from the drying effects of the most intense heat.
Spray, I wouldn't worry about doing any spraying unless you're in the cooker anyway. early in the cook spraying will just inhibit the formation of the bark. As the boss sez, if you're lookin', you ain't cookin'. Spray if you get a heat spike after adding fuel and you need to bleed of a little extra heat. Makes you look smarter than just standing there with the door open :wink:
There's lotsa rubs in the recipes section. Use one with some sugar, it'll help "candy up" the surface and hold in the juices. Turbinado sugar works best as it is burn resistant longer than white or brown sugars. Use mustard as a pre-rub wetting agent to help bond the rub to the meat. Makes a world of difference.
Read the brisket thread listed in the "Roadmap" thread. There's an article in it that will really help you understand what you're trying to do with this big hunk o beef for 12-20 hours.
http://www.bandera-brethren.com/index.php?name=PNphpBB2&file=viewtopic&t=2854
Don't be afraid to finish in the oven. You'll be tired and there's nothing wrong with some easy at the end.