This episode's headline: The Debate: As the Media See It; El Salvador: Peace at Hand?; Peres Talks About the Future; Portrait of an Artist. The guests include In New York: EDWIN DIAMOND, Media Critic; SHIMON PERES, Israeli Prime Minister; In Washington: DON OBERDORPER, Washington Post; Reports from NewsHour Correspondents: ELIZABETH BRACKETT, in Michigan; MARY McDERMOTT (WETC,), in St. Louis. Byline: In New York: ROBERT MacNEIL, Executive Editor; In Washington: JIM LEHRER, Associate Editor