For competitions I trim that hard fat and also trim the fat cap on the back side only in the point area to get more surface area for rub on the point. You don't have to do any of that, but the fat will just end up in the drip pan.
As far as cook time, with the temp plan that you mentioned I'm guessing that you will be looking at 75 minute per pound, so around 12.5 hours. You also want the brisket to rest in a dry cooler or something similar for a couple of hours. This lets the juices recirculate.
So that's about a 15 hours cook and hold time. If I did my math right that would mean starting the fir at about 2AM and getting the brisket on at around 3:00 - 3:30AM.
As I'm sure you have read, the brisket will be done when it is done. The two hour rest time also acts as a buffer in case it takes longer. If it's done earlier then you jusr let it rest longer. Cook it until the thickest part of the flat is probe tender. The point will take care of itself.