I can't cote. However you could have a system where you either spawn in a random uniform or you could pick it yourself at spawn or find other uniforms that are better camoflaged or armour if it exists.
If anything it is more likely to see soldiers roaming aorund than civilians armed with a handgun. I dont think they should be hostiel to everyone. Just zombies and people who fire on them first. Being in a squad of say 6 men taking them on single handidly would be a bit silly... However having a group of 4 or 5 people (or even 2 if you are good enough) to take them out and use their military grade gear etc.
I think only players killed by zombies (or certain types of zombie) should be re animated. Getting shot wouldn't do that. It is a great idea, you could defeat this thing happening by burning the corpses so they can't come back.