Google+ hashtaging words with the hash symbol in it

Not possible the way you're doing it, but if you go to the Profile page of the person and click the circle that they're on, you should get a checklist of all your Circles. Uncheck the one you want to remove them from and check the one you want to add to.

A nuisance, sure, but currently the only other way to remove from one circle and simultaneously remove from another.

It is very unlikely you will find that out.

• It would require monitoring all G+ user posts from 3rd party site, which would be very inaccurate due to permissions (circles), not to mention disliked by Google.

• If someone got the permission from #angry birds to track notifications and made the 3rd party server/site, mostly no one would bother to do this.

• Downloading scripts could work (if those existed) but it would only make a list from people you circled (and other way around).