Help slicing my 2nd brisket correctly

Yes. cut across the grain, stay 90* to grain as it changes.(you may need to make adjustments)  If you get a lot of bark you can score the meat before cooking for a visual later. Good luck.

That looks correct, if it's that 90 degree angle to the grain. Put in three toothpicks now on the red line. In that way, when you lather it up with rub and can no longer see the grain, you'll just put your knife next to the toothpicks and start cutting. You use three toothpicks in case one pops out during rough handling. 

That's a full packer, right? You should separate the flat and carve as you have indicated (you might want to notch that reference so you can tell when the meat comes out of the egg looking quite different). The grain on the point runs different, but it's easy to tell because of the fat.