Rick Danko, 56, plaintive vocalist and bass player with The Band, Friday, at his home in Woodstock, N.Y. Cause of death was not immediately known, but Danko (who was arrested in Japan for heroin smuggling in 1997) had an acknowledged drug habit . . . Actress Shirley Hemphill, 52, the wise-cracking waitress in the '70s TV series "What's Happening!!," of natural causes, Friday, at her home in West Covina, Calif. (Another "Happening!!" cast member, Mabel King, died Nov. 9) . . . Inam Abdel Raouf Arafat Al Kidwah, 82, the eldest sister of Palestinian leader Yasser Arafat, after a lengthy illness, Sunday, in Gaza City. She has been described as the mother figure in the Palestinian leader's life after his mother died when Arafat was young.