I don't think you will be able to literally ress the npc, you would have to respawn him which wouldn't look so good.
Instead set bytes1 to 7 (no idea how to do this in Lua - there is a set byte command but I don't understand the structure). This will make the npc appear dead. Either set health to 1 or make it untargetable to get the dead effect to look realistic.
The commands for bytes are as follows:
To control multiple npc's, look at my reply to this post: http://www.mmowned.com/forums/world-of-warcraft/emulator-servers/questions-requests/314442-quest-script-not-sure-how-code.html (I can't be bothered to type it out again).