So I have iCloud enabled on my Mini and MBP. Will everything in my Documents folder automatically be shared via iCloud as long as Document and Data is checked, or is there some other step I have to take?

When you run Adobe InDesign next time... everything will be synced.
All Adobe goodness...Mmmmm...

Here's a good explanation. It's 3 pages, if you scroll to near the bottom of the first page it starts to cover the doc and data sharing.

From what I understand unless it's data from Apple or an iApp if you exceed your free 5G you would need to purchase more.

Yeesh. This is above my pay grade. If I've got the same ID (or Pshop, or any other) file in a projects folder in Documents on both Macs, and I make changes to the file on Mac A, are you saying those changes will appear on the file on Mac B when I open it?. And if I make further changes to the file on Mac B, they'll appear on Mac A when I open it the next time?

I've got 55 gigs of iCloud space, so size shouldn't be an issue.

That's the way I read it.

Doesn't seem to be the case. Last night I made an arbitrary change to a Word.docx (that was last updated in Feb, 11) in a particular folder in Documents on the Mini. Just opened the same doc on the MBP, and no change. Me scratching head.

In your Save window you should have a choice for iCloud in the pop up menu where you choose a folder.

No such animal. At least not in Word or ID. Maybe it's gotta be an iApp file, like Pages or Numbers? Maybe I'll save a Word file as Pages and see what happens.

Yup. Opened a Word file in Pages, and when saving, iCloud is the default in the location drop down. So obviously, only Apple file formats are compatible with iCloud — at least for now.

I need to sync entire job folders — a packaged ID project would include fonts and image files (Pshop and AI) as well as the production file, plus reports and instructions and other documents — so It's probably more efficient to just transfer files back and forth via file sharing (or bluetooth sharing) as I've always done anyway.

Now, if Apple wants to buy Adobe and MS, and make it all iApps, that would be just da bomb!

Right, after reading farther it's Apple apps only. That's too bad, could be a handy thing, except for the fact that I bet it's not backed up with Time Machine so you're relying on Apple to not lose your stuff.