I agree with Phil but I would put the briskets in one of those big church roasters overnight set to 180 degrees. My roaster will hold three medium sized primal briskets fat cap and all. You will need to add about 2 pints of water to the bottom of the pan. This kind of accomplishes the same thing as the warm cooler, it is probably 6 of one and half dozen of the other, and I am sure that what ever method you use they will turn out great. When I cook brisket like this I usually shred the beef just like you would with pulled pork and add back the juice at the bottom of the roaster. This makes great sandwiches. In fact the more juicy and wet the bread the better I like it. I usually never use BBQ sauce but some people do so besure to put someon the side when you serve it up. The overnight cook off can sometimes loosen the meat so much that it does not want to slice thin, so if you slice it you need to slice it thick. When you trim the fat cap and start to slice it up you will know whether you need to slice it thick or thin or even consider shredding it. Just make it up as you go along and all will be fine.
I would not worry to much about the fat up or down decision. I like to put mine fat up so the fat will liquefy into a natural baste and run down into the meat. This takes the rub flavor on the fat down to the meat also. I use a fork and pierce the fat a lot so that the liquid can find its way to the meat easier. For as long as a brisket has to cook I am not sure that it makes any difference whether you cook it fat up or fat down. Liquid tends to flow from high concentrations to low concentrations so I would guess that the liquefied fat would flow up into the meat as easily as it would flow down into the meat. I have fixed briskets both ways and do not see much difference between the two.