A fly ball caught from the initial throw is played like any other ball. It is not like kickball where the player would be considered out. A player must be hit at or below the waist to be out. The offensive player hit above the waist is not out and should continue to attempt to score. The offensive player must tag the hand of the next player before that player can run.
Runners can use defensive players as shields.
You can use more than one ball with larger groups when players understand the game.