According to witnesses, the pilot initiated go-arounds after 2 attempts to land. One witness reported that during the 2nd go-around, the aircraft passed by hangars near the departure end of the runway at hangar roof height with full flaps extended. Shortly thereafter, the airplane was observed to pitch up, yaw/roll to the left, then pitch down & collide with a bowling alley roof. During rescue, the 3 rear seat occupants were extracted from the wreckage. The two front seat occupants were still entangled in the aircraft, when the building & airplane began burning. During a post-accident investigation, the propeller control was found to be 1-1/4 inches from the full forward position & the flap jack screw assembly was found in the fully extended position. Also, the airplane was approximately 160 lbs over its max gross weight limit & its CG was approximately .3 inch forward of its most forward limit. Additionally, no record was found that the pilot had a formal checkout in the high performance airplane.