As regards HP variables issue: it's because of Delay object, using its event or action will break selected objects list.
But you can make delay between animations with 'on animation finished' event (first uncheck "loop" in ''hurt animation properties and adjust animation speed)
Also, do you know you can change sprite's angle without rotating? Just set No Rotation in obj' properties
Also, why do you use angle expression instead "set angle towards object"?