on your purchase and welcome to the world of Nexus!
I used the Steinheil Flex screen protectors and was not impressed. They are easily scratched and gouged... and I have no idea what gouged mine. I'm going to try XO skin next.
If I might, your extended battery will add roughly 17% power to your phone. In addition, I would highly recommend Juice Defender Plus.
The free version on default settings increased my usage time by half: the Plus version - in balanced mode - almost doubled it. I can easily go from 5 AM to about 9 PM or later on a single charge, with web surfing, texting, occasional calls and nearly constant Bluetooth streaming to my BT stereo headest (if you're looking for a good set, the Rocketfish RF-MAB2
Lookout (or AVG) Mobile Security is very important.
Finally, you don't need to pay $90 for a Samsung horizontal dock: I am a big proponent of Capta
and can't recommend it enough. It's a tripod mount and also serves as a bedside stand for my Nexus (or any other smartphone, for that matter) and it'll last forever. For $34 shipped it's an unbeatable value.
If I think of anything else, I'll let you know.