This episode's headline: Newsmaker; Halfway Mark; Departure. The guests include ROBERT RUBIN, Secretary of the Treasury; REP. CHRISTOPHER COX, [R] California; REP. JOHN CONYERS, [D] Michigan; THOMAS GIBSON, Gates Corporation; DOUGLAS BRAGG, Trial Lawyer; CORRESPONDENTS: BETTY ANN BOWSER; KWAME HOLMAN. Byline: In New York: ROBERT MAC NEIL; In Washington: JAMES LEHRER