POOR PLANNING/DECISION BY THE UNIDENTIFIED CESSNA PILOT BY MANEUVERING IN BUSY AIRSPACE NEAR THE ARSA WITH NO ATC COORDINATION OR TRANSPONDER SIGNAL; NO TRAFFIC ADVISORY BEING ISSUED BY THE APPROACH CONTROLLER; AND INADEQUATE VISUAL LOOKOUT BY THE FLIGHT CREW OF THE BOEING 727. A CONTRIBUTING FACTOR WAS THE LACK OF AIR/GROUND COMMUNICATION BY THE UNIDENTIFIED PILOT.