Darklor01
Might need to stop sniffing glue
All of your Xbox LIVE settings, saved games, and other miscellaneous options are saved to the cloud. You would have to redownload the games again, but if you have an external HDD, that's mitigated as well.
For most of us, it will be plug-n-play.
If I will be keeping my XBOX One and want to have the games on both, can I use a computer to copy the external drive from my other system to another external drive so I have everything on both system using two different external drives and just go from there?