well i can only guess when a fish is happy but usually if its said it will just mope around at the bottom of the tank. anyways about the air thing bettas have a labyrinth organ so they actually breath air off by poking there head to the surface.
beetlebs: gouramis and bettas are in the same group because they both breath air from the surface with there labyrinth organ. all this air breathing is normal. (btw i own a 4 year old betta and a three spot gourami :D )