For the zombie respawning being a problem, htere are 2 possible solutions.

1.) On an escape map we could make multiple spawn points for the zombies so that once the humans pass a certain point on the map the zombies will start spawning closer to the humans.

2.) The second solution is in the map development itself. We could make some pmaps like zombie panic where the humans run around in like a building and have to complete objectives to gain access to better weapons, and eventually a chopper or some way to escape. We could then have a room right in the middle of the map where the zombies could spawn. As i said in the other post this is alot like zombie panic! so it is possible.

Also, i think res said about having the humans need to be hit more than once that is also an idea from Zombie Panic!, and only the alfa zombie should be able to infect people, which would then turn the human about 30 seconds later.