With a pump you have to 1) put your index finger on the pump release by the trigger, 2) pump the gun, 3) put your index finger back in the trigger guard, 4) and finally fire......Am I missing something
Yep. On a pump, the slide action releases once you pull the trigger. You only have to release the slide with the slide release to work it the first time IF the trigger has not been pulled. On a Mossberg, you can even release the action with the third finger, keeping your trigger finger in place if you like.
As has been stated, the pump shotgun will fully cycle the action regardless of the round you are firing, as long as you do not short stroke it.
The shucking of the action is an attention getter. With a normal but angry/misguided person, it should do the trick. With hardened criminals it may not. It will get their attention though. Just like drawing your handgun, do not shuck the action on a pump shotgun unless you intend to use it.