Also, just a side point: if your Steam is online, and you right click on CK2 and select "do not keep this game up to date", it will still download patches because the Steam system automatically updates games when you run them in Online mode, even if you have told it not to. This is WAD and has been stated in the Steam forums.
The only way to keep Steam from ever updating a product is to put it into permanent offline mode.
Just wondering, does anybody NOT think this is idiotic and misleading?