LBJ TELLS MOYERS TO KEEP STATE DEPT INFORMED OF DOMINICAN REPUBLIC EVENTS; MOYERS, FORTAS UPDATE LBJ ON MCGEORGE BUNDY'S TALKS WITH GUZMAN, CYRUS VANCE'S PRESS BRIEFING, LOYALIST ADVANCES, CEASEFIRE; MCNAMARA DISCUSSES VANCE'S ACTIVITIES, US TROOP ACTION