Game save (Assassin's Creed: Revelations)

I have bought the key to after the release to play multiplayer, but for now decided to properly brush the single. As I understand it, the story of Desmond at the moment does not plow, therefore, arose, here are two questions. Where are the save game and if you reinstall the game, you fly off those saves? In any case, will have to endure the crack and put a clean version after the official release, and nothing to play not hunting to after again to replay the story.