When I'm near the Front and leave for a beer run, I try to acknowledge those I pass ("thank you", eye contact, "Old Man Coming Through") on the way out. Usually they'll recognize me on the way back, making it easier to reclaim my spot.
Man, it is hard to get back to your spot. If you get a close in spot, you've essentially agreed to not drink beer that night. Make your "concert friends" for the night. I tend to stand near the back now (old and tall), but even when you are a legit front rower, you feel like an a-hole trying to get back to your place.
Pretty much agree with that whole list. Take your photos in the first few songs and then put it away. Enjoy the moment. And at the end of the day, be considerate to those around you, but also remember that this is supposed to be fun. If your tsk-tsking someone for dancing... you're the a-hole. Lighten up.