The delay is easy, just put wait =1 and isAiming=1 at bottom of the "on any touch end" event.
I am terrible at calculating angle logic (and am minutes from heading to Disney World) but you will need to change the values in the "is in touch" event (angle(Touch.X, Touch.Y, CatapultBlock.X, CatapultBlock.Y)) to restrict the draw to your required angle... maybe someone with a better head for that can give you the correct values. You might want to ask just that part of of your question in the forums again "Correct logic to limit physic catapult to 0-20 degree firing angle".
If you need to reset the camera back to the catapult after it scrolls to the shot pig you can use a subevent under the "Else" portion of the "Is aiming" event that uses event "Is Physics sleeping" with action scroll to catapult.