I’ve heard that cats sometimes ‘taste’ the air with their tongue to aid their sense of smell. I know my cats open their mouths if they can smell that someone in the kitchen is cooking fish or meat, though I’ve never seen a cat stick its tongue right out like a dog. I think they’re much too proud for that 😉
Cats do NOT pant in order to lower their body temperature as dogs do. Cats DO pant if they are very, very frightened. Stroking the cat usually calms them down, although they might be a bit defensive. But if the cat keeps panting to where they are hyperventilating and/or seem to be gasping for air — if you can see their belly moving up and down indicating that they are working hard to breathe — then its time to get them to a vet, fast!