The pilot reported the airplane touched down before the halfway marker on the runway, but the airplane bounced. He recovered from the bounce and applied heavy braking and the airplane began to veer to the left. The pilot released the left brake and applied more right brake to straighten the airplane. The airplane continued off the end of the runway where it contacted a ditch separating the nose gear resulting in substantial damage to the firewall. The pilot recently transitioned to this airplane and stated he did not realize that the airspeed indicator was in knots and not miles per hour which resulted in a faster than normal approach speed. The pilot stated he did not check the weather prior to landing which resulted in him landing with a 3 knot quartering tailwind.