A: The handle is 3.5 inches long and the shaft is 4 inches long.
A: Screwdrivers should never be used as a hammer
A: Depends on how hard you are going to hit the screwdriver light taps are good, but if you want to hit your screwdriver hard you will demolition screwdrivers. I know Millwallkee, Klein Tools, and Dewalt sell Demolition Screwdrivers. I should just say yes you can in a pinch.
A: Anything can be used as a hammer in a pinch.
A: No, this is not a pentalobe screwdriver.