An upper room or balcony with latticework was common. It allowed air to flow freely and offered some privacy, but lattice was easy to break.
Baal-zebub (which means lord of flies) might be a mockery of a Canaanite god named Baal-zebul (which means Baal is prince). People later used this god's name for Satan (see study note on Matthew 10:25). Ahaziah worshiped Baal, like his father Ahab.