“Amistad” producer Debbie Allen, cast member Djimon Hounsou and sports legend Earvin (Magic) Johnson plan to speak to an audience of 600 Los Angeles high school students today following a screening of the new Steven Spielberg picture.The students, from 13 schools, have been asked to come prepared with questions for the panel. Allen will speak about her 12-year quest to bring the story of “Amistad,” a historical drama about a slave revolt, to the screen. DreamWorks, Spielberg’s production company, has provided the schools with “Amistad” study guides. The screening, at 9:30 a.m., is being presented by DreamWorks and the Magic Johnson Foundation, which raises funds to support community-based organizations in inner cities and HIV/AIDS organizations specializing in education, prevention and care. It will take place at the Magic Johnson Theaters, 4020 Marlton Ave., Los Angeles.