This was an interesting write up, and more diverse than one usually encounters. There is one more interpretation that I'd like to give you, although I can't remember the exact source.

There are modern day pagans who believe that the Medusa was a high priestess and the snakes on her head were a metaphor for the priestesses in her temple. She was discredited as society evolved towards a more paternal pattern and turned into a monster.

But snakes have always been a pagan symbol for divinity. Think about the priestess at the oracle of Delphi, who bore the title of pythia. Think about how Christianity actually dislikes snakes (Saint Patrick chased them out of Ireland and a snake was the reason mankind was thrown from paradise.)

I'm not saying I know it all, but there may be more than meets the eye to this myth. ;-)