Multiple characters are fine, but if you start to slack off on posting for them, we'll have an issue.

You control when your character dies except in two circumstances: 1) You break a rule and do some sort of overpowered nonsense, in which case your character may be killed off to keep the roleplay realistic. It's not fair to the others for your character to be the god of zombies and 2) if you become so terribly inactive that you hold the RP back.