1. Shelf placement for each piece. Here's how I do a full packer in my #1. Put the point fat side DOWN on a lower shelf (the fat will shield the point from the direct heat of the smoke box). The point can take more heat and be closer to the heat source. Put the flat fat side UP on a shelf above the point. The point will shield the flat from direct heat, and the fat on top of the flat will keep it moist.
2. Cook temp and what temp to pull each piece for FTC rest. The goal would be to slice the flat and pull the point. Before pulling the point (for pulled beef), try it sliced. It is delicious! I like sliced point better than sliced flat. The point is also great for burnt ends. You want to take the flat to about 195, and the point to 200-205. Probe each separately if you have two wired probes laying around. With the shelf arrangement as I described, both will probably be at their finished temperatures around the same time. If not, definitely wrap/rest each piece as it is done. Look for the meat to be floppy and kind of jiggly like jello.
3. Now that I have two smaller pieces, how will that affect cooking time? Trying to eat around 4PM tomorrow. Cooking time will be shorter than if the brisket were whole. Base cooking time on the weight of the larger piece. The additional meat mass in the smoker might add a little extra time, but probably not that much in a 2D. It will take 1 to 1.5 hours per pound at 225. So that's 7 to 10.5 hours, plus a 1 to 2 hour rest. So I would say start it 11.5 to 12.5 hours before you want to eat (start between 3:30 and 4:30 am), and if it is done before that, it can rest in the cooler longer, even up to 5 or 6 hours no problem. My advice is if in doubt, start earlier, and rest longer. Brisket that is not cooked and rested long enough is not good.