If you use the file syncing that comes with the Creative Cloud desktop application then as you save changes to your InDesign file, you will create a new version that sync up to the cloud storage. From the Files page at https://creative.adobe.com/files you can see when each version was created, and you can revert to an earlier version.
I have produced many CS6 InDesign Documents in the past. If I purchase Creative Cloud, will I be able to open and edit my CS6 InDesign docs? I would like to be 100% sure that this is possible before I purchase.