I own CS6 InDesign (and other apps). I don't want anything to happed to these apps. But, I do want to download the CC versions. Can they both reside on my computer separately (As I have CS5 apps along with my CS6 apps)? How do I make sure the CC apps don't change, overwrite, or "take over" when I work in CS6? This is a source of confusion, and I'm seeing various answers that make me worried about moving to the Cloud.
They will coexist, just like your other versions. Lots of us are working that way.
Installing CC will make it the default application, though, for opening ID files with a double-click. And the same version-to-version problems exist trying to open CC files in CS6 or earlier.