By far the most important rule is: "Be aggressive enough, soon enough."
I have seen several friends get hurt and one almost get killed because they took the "too little too late" approach in an effort not to offend anyone. Taking immediate and decisive action does not make you any friends...it usually upsets people (or gets you sued on a consistent basis :rofl. I always remind people that Hollywood is not real. Subtle signs of aggression can turn deadly in an instant...stay on top. Don't be scared to be scary. After all, its a righteous fight...isn't it?
#2 is 'Anything you bring is going to be infinitely more effective than anything you left in your safe'.
#3 is something that a Navy Seal once told me, 'never fight fair'.
After that I think the rest of the advice is sound, except for, "If your shooting stance is good, you're probably not moving fast enough or
using cover correctly." I've trained long and hard to figure out how to shoot from cover. If I've got good cover, I can afford to use a good shooting stance. It's when I don't have good cover that I need to not worry about my stance.