I pull the head and get the whole shell from the body with my thumb, works well if you have decent shrimp that aren't paper shells. Leaves the side of your thumb between your skin and nail pretty raw if your doing a large amount. With enough practice tho you can pretty much push through the shell of the shrimp with your thumb where the shell meets the legs and slide down and pull the shell off attached to your thumb. As for depooping just a sharp parrying knife down the back and a quick dip in heavy flowing water. I've never done it on shrimp as it seems a bit ridiculous, especially when your peeling 200+ shrimp. But the skewer thing made me think of cleaning spiny lobster. After we caught them, to clean them you would break an attenae off, shove it up the rear end a bit and twist around. Separates the sphincter mussel from the back of the vein and when you pull the head off the whole vein comes with it.