I was wondering if there was any save file out there that will give me the Zombie achievements (Opening all the doors without getting caught on fire etc etc) Anything would be appreciated
Have some friends start a game and when they have one door left, join them. There is no such thing as a savegame for zombies achievements.
A GPD? That won't get you any achievements either. You can follow this tutorial to mod your gamerscore. There's virtually no risk if you only plan on doing one. http://youtu.be/qW9b8mjP4hM