you said in #2 that if they came at you and you didn't know if they mean you harm to "draw my weapon and yell Get back or something like that"
you cant pull weapon and use as an intimidation tool. as i understand the law its that if you pull your weapon you pull the trigger. its not an intimidation tool.
I don't think most folks consider that as an intimidation tool. Issuing verbal commands while drawing your weapon with the intent to defend your life isn't uncommon to do (see just about any defensive training). It all depends on the situation and how much space and time you have available though.
You should be prepare to pull the trigger each time you draw, but each situation will determine whether or not you shoot. If you pull your gun and your attacker immediately retreats, then you probably don't want to shoot someone in the back because of a rule that your SDA instructor casually hit on in a CCW class.