Mind you, if I go with the physical box and CD option, I could install on a friends computer maybe and save the up-dates from his?
Not quite, no. The way Impulse updates is by comparing your installed game files with their up-to-date files on the distribution network. If there's a difference, Impulse just downloads and over-writes the necessary files directly.
In theory, this does mean that you could install at your friend's house, update it by logging in with your Impulse account (you will also need to register the game to your account before you can download updates), copy the installation folder to a USB drive or something, and then paste into your install at home, overwriting everything. I think Impulse updates the version string in the registry for its own purposes, but as you're not online anyway I don't imagine missing any registry updates from the patching process will mean anything.