How many times have the Kings been at .500 after 8 games, and how many of those teams make the playoffs?

Eight times. Half of them make it. Kings are a playoff team 50% (4/8) of the time when they're at .500 after eight games. If their record is better than .500, they make the playoffs 71% (12/17) of the time. If worse than .500, they make it 44% (7/16) of the time.