No. Just click the 'go offline' button in Steam before you disconnect from the internet and you can play for a while without being connected. About 30 days in theory.So after I install it following the above procedure including the updates, would I need to be online to continue playing the game?
I've heard mixed feedback about how well Steam's offline mode works, if you don't have any internet access on the computer you'll be playing on, you might need to give the game a miss.