Flap, I am literally in love with your game ideas. I want to play that exact game you just described, except game ending in 30-60 days SUCKS. I say 3-6 years.
Also, my idea for a starting squad:
(PLAYER CHARACTER - absolutely necessary.
(MUM - Emotionally, bad idea. Watching the woman who shot you out of her vag get eaten by zombies would mess you up.
(DAD - Randomly generated types. Abusive, perfect, means well, none-too-good, good, drinker, all that dad stuff.
(BRO/SIS - Randomly generated possibilities and types. Not everyone has a brother or sister, so make it not always available. Types would be more generalized then specific. Nice, mean, bully, protective, etc. Also younger/older, specific age provided. You're not gonna leave your 3-year-old sis, are you?
(BOY/GIRLFRIEND - Not always available. Interchangable with wife/husband, but I think it would be better to keep this one simpler. Or, in character creation (which we'll get to later), you could specify. Specify gay/straight, single/taken, relationship/marriage, or let fate decide. Or let fate decide everything but gay/straight. I don't think gay people would want to be forced to be straight, and vice versa.
(THE BEST FRIEND - Really good friend. Since childhood. Definitely want to bring him/her. Who wouldn't want a good friend to die with you?
(1-3 GOOD FRIENDS - Like best friend, but not best.
(PETS - Dogmeat, a la Fallout? Anyone?
And basically that's it. You can't bring everyone. Car size, number of cars, etc. Technically you could bring everyone if you had lots of big cars or you go on foot, but food runs out fast that way. Traveling in large groups would also attract Z's. Probably the best size is 2-6...
Also, character creation would be vital if all this is included. Big family, small family, lots of friends, no friends, pet, no pet... But don't give the player too much power. Create themselves all they want, but sociality and things like that should be half-player, half-fate.
I had more ideas earlier, but I forgot many of them as I was typing. Please consider my thoughts, since this has taken a buttload of time.
Oh yeah, let the player type in the damn names. Seriously.
I'll post any more ideas I get. I don't know anything about design, I just have a very active mind.