I can only speak for no. 4
And what you see in videos from the middle east is a case of nothing threatening the helicopter, leaving it free to fly high and fire down on targets. Giving it a nice tight cluster like you say.
But when you are in this environment, where AA and SAM launchers are everywhere. The choppers are forced to fly low, use tree lines or terrain as cover for pop-up attacks. Since they won't be up high the trajectory for the rounds will be flat and spread in a long line.