The metal skin of the aircraft will sheild the occupants inside(Faraday's law comes in handy here). Most damage is done at the extremities and antenna's, electronics if it was a direct hit. I've seen a King-Air that got hit, it smoked the tail pretty good and came out around the strakes at the rear of the fuselage.

As far as knowing it hit you, I have no idea, but I'd imagine it'd be loud!!!