In 1939, the NAACP's Spingarn Medal went to which contralto, famous for both spirituals and opera?

Who won a 1939 Oscar for playing Mammy in "Gone with the Wind"? In "The Wizard of Oz" (1939), which actor played "that man behind the curtain"? "The Kingdom of Swing" (1939) was the autobiography of which bandleader? In which 1939 film does Laurence Olivier's Heathcliff say, "The moors and I will never change. Don't you, Cathy"? Which 1939 novel opens, "To the red country and part of the gray country of Oklahoma, the last rains came gently"? Which 1939 film includes the famous line "Toto, I've a feeling we're not in Kansas anymore"? In which 1939 film does a senator declare, "You all think I'm licked. Well, I'm not licked. I'm going to stay right her… In which 1939 film does Rhett Butler tell Scarlett, "You should be kissed, and often, and by someone who knows how"?