Yes, as an alternative to dropbox, for documents, music, etc.  Phone app and ability to access anywhere.  Keeping docs safe from computer crashes.

No. I wouldn't limit it to my clients, but that would be where I'd have my successes.

My initial thought is, sign them up for the X months free , after installation. Show them how to use it, it's capabilities, and voila! they're hooked and I've got another source of revenue.

Yes, I'd deliver milk if I could make a buck at it.