For former Rockville Centre Fire Department Chief John Busching, answering the call on Sept. 11 meant crawling into the darkness of a collapsed World Trade Center, through unstable rubble and burning debris, to reach a man trapped beneath the wreckage. Busching, then an NYPD Emergency Service Unit officer and paramedic, arrived at Ground Zero around 7:30 or 8 p.m. after being redirected from Floyd Bennett Field in Brooklyn. He had initially been…