A: No, it’s not the Hand/Keeper Limit card which is discarded at the end of the active player’s turn. The Rule stays in effect like any other unless it is specifically replaced or discarded with an Action. The discarding which happens at the end of the active player’s turn is the active player discarding down to the Limit themselves.

Since Limits only apply when it’s NOT your turn, the non-active players discard down to the limit as soon as the card is played, while the active player does not have to discard until the end of their turn – since at the end of their turn, they cease to be the active player.