Icloud backup of single files?

[Sonicrobby]

Ill start of by saying I've never really used the iCloud backup feature. I'm usually one to restore my firmware often, and setting it up as a new iPad every time (I notice it's a bit quicker than when I restore from a backup). But I've got 1.7GB of documents in an app which is not yet capable of iCloud sync. So I'm just curious as to what would happen if I go to iCloud settings, and enable the backup solely for that app; restore my firmware as a new iPad; install the app from the app store; and then restore from iCloud backup. Would it basically just restore all that app data? Or am I thinking of this wrong?

Actually, can I restore from iCloud backup at any time? Or can it only be done when first setting up the iPad?