I haven't been to Coober Pedy but from photos I've seen the homes are dug into what seems to be pinkish clay. As you know, dry clay is sort of chalky, so I guess dust would be a problem if you're inclined to drag your feet or bump into walls.

The summer rains in the north often bring with them spectacular lightning storms. The "light show before it comes down" would refer to the lightning before the downpour, I'd say.