Not much of a download.
Never played the dlc for the first so I wouldn't know how long those were but I've heard that one of them were at least 90 min long. All you do is get to the location, look for some tags if you want and plant the monument at one of the predetermined locations. If you had to pay for this, it would be worth the cash unless you want to see what Bioware came up with for the first normandy.