> It's fine to me. 
> 
> What if the zombies don't get any food? Can they starve?

They do not starve. The zombies rot though, eventually becoming skeletal forms, which are more lethal due to their sprinting nature, but are more vulnerable to projectiles (as they'll shatter, with less muscle, fat and ligaments to hold them together). 

In the middle of beefing up the dead section, so that everyone knows what they're up against. As is already stated, decapitation or total annihilation is the only sure fire method of killing either zombies or skeletons. Zombies soak up bullets like a sponge, skeletons will be shattered by them. Their strength will vary from creature to creature, with skeletal forms being weaker as they lack muscle, and are more brittle.

Skeleton forms are not complete skeletons as you might expect from a fantasy roleplay, but rather, very skinny zombies with ligaments and some muscle still in tact. 

The undead will rot to a certain point, but not to a state of total re-death or paralysis. 

So, to sum up:

Skeleton forms: ![enter image description here](http://www.yellmagazine.com/wp-content/uploads/2014/10/xcorpse.jpg.pagespeed.ic.OhmoOnD34g.jpg "enter image title here")

Zombie forms: Anything not that badly decayed.