I'll also chime in on the what did he say question with it being Andrea is infected. The everyone is infected sounds pretty stupid to me. Especially when they already established that if you are alive and infected, you quickly get ill and die.
It's shown in the comic (issue #015), that when someone is killed/dies they become a zombie, no matter what the method of death is. Being infected with the zombie virus doesn't kill you, it just means you become a zombie when you die.
The zombie bite kills you by opening a wound and delivers bacteria (could be poison, venom what ever you like) into the body that kills you. Like a cat bite, the puncher hole isn't too deep and you won't bleed out, but their mouths are full of bacteria which will get really nasty if you don't clean it out.
They're a bit different from the normal 'I bite you, you're a zombie too' kind.
As for the military stuff, meh. I really couldn't give a crap about how good you think your armed forces are. In this story, they failed. The end. The zombies won, zombie apocalypse has happened. If we were following an group from the forces then it would be relevant, but as far as this story goes it matters little more than the fact they the sky is blue and the grass in green.