i think that the laying with back half upside down is a sign of gravidness, but i dont know about the vent thing you're talking about, or the mouth open thing, she could be sick and gravid.

i noticed in your post, it said that she had started to shed, and should be done some day soon. does that mean it isnt coming off at once? if so, it should come off all in one piece, raise humidity and soak it. or do you mean that it went blue and cleared up, and should shed soon? either way raise the humidity.