I don't think your AI problem is a major one. Running it using spread values/For Loop/State based, it would be simple to have wander/run states for NPCs and then switch them over to zombie once bitten. You could potentially just have them "die" and then spawn a zombie on them later when they wake up and "turn".
If you want some help on AI (although you seem perfectly capable at MMF2), I'm happy to lend a hand.
I like the concept though, what sort of game-arc are you looking at? Is it something that basically goes on forever and you're just challenged to see how long you last, or is there a definite ending? Like having a radio that you can listen too, that might (just might) broadcast the location of a safe zone, but you might be out hunting squirrels with a stick when it comes through...
My only other comment (without wanting to overload here), is that there is ALOT to this project - is it going to all be intro'd gradually or is the player dropped in like eat,customise,barricade,sleep,hunt,cook,store OR DIE? Wonder if your story setup could be that (because you're somewhere remote) you have a few "days" to get yourself setup before the infection reaches you. Give the player some time to become accustomed to the survival elements of the game before they have to deal with flesh-eaters...
You mentioned the sims.
Would be cool actually if it starts off with a sims vibe. Hunt animals, store them, cook, sleep, harvest firewood, customise your gun for hunting, then there's news of a zombie outbreak and you gradually start getting more and more of them come to visit.
Anyhow. I'd hate it if someone came to my thread and started suggesting loads of stuff, so I'll shut up. Cool project though, will check back soon,.
Oh hey, I missed that forgot these forums existsed.
Most of the concepts I listed here are probably dated and I've since revised a lot of it, but you've made some good suggestions. I've been working on another project at this point, hopefully it will pick up and generate some kind of income