i moved my whole steam x86 file onto a new drive and the only problem i had with it was that it took a while with 70gb of games, but if you do move disks. all other documents dont need to be moved, because when you set a new install directory it lets the other folders know, plus the shortcuts on steam already launch to the location of said folders. make sure you set your steam install directory to the new steam directory location, as well as re-write any shortcut locations to the new one, otherwise games would install in a new steam directory where it was previously and you wouldnt be able to open steam with shortcuts
if you want long-term storage, go for hard drive, if you want to be able to take it anywhere without having to have a hard drive adapter for laptops, go for flash