[MR] What does a Principality include?

[Elspeth Payne]

Your pardon, good gentles, but for those of us who weren't around ten years ago and haven't lived in a place with a Principality - so that we can keep up with the conversation swirling about, could someone please state clearly what-all is included in the creation of a Principality?  
I gather it would have a Prince and Princess who are not heirs to the Crown, but who can hand out Kingdom awards in place of TRM or TRH.  Are they decided by tournament as well?  How long can they hold office?  What's different between the court structure of a principality and that of a barony, besides rank of the rulers?  Does a principality have to have a certain area in square miles, or average population size?
Thank you for helping me improve my general awareness of SCA practice and procedure.
For the record (though, alas, it makes no difference in the price of gas) - I've really enjoyed the events I've been to in other regions of our fair Kingdom.  I've met the nicest people, and it's fun to go new places and get new ideas. I like road trips.  I feel much the same about really far out-kingdom events I've been to, but there is something about having folks just a state or two away that helps me think I really should see them more often, seeing as we're on the same team and all.  If we were to subdivide Altantia, the same nice people and fun events will still be a state or two (or three) away.  I liked things better when the deciding factor was no more than the time I was willing to spend getting there and back.
Sorcha Prechan
 
Blue Celt