You have some cool ideas for zombies and stuff. I would like to contribute an idea, myself. Here it is: Zombies could have a major hunger that gets bigger after amounts of time. Now, how I think it should work is the zombie doesn't necessarily get faster or stronger, he just gets more desperate to eat, increasing the chances of it eating a nearby body. The zombie might also be louder, and have less of a chance to attack a nearby survivor while eating a body, since it wants to eat so bad. Okay, so this idea may sound stupid to you, but I just wanted to contribute here. :D