CAR BOMB KILLS 8 AT POLICE STATION IN BAGHDAD SLUM
Station wagon packed with explosives blows up inside police compound in one of Baghdad's poorest slums, killing car's occupants and at least 8 others and wounding more than 40; hours later, two American soldiers are killed and four wounded in ambush in same Baghdad neighborhood; no one claims responsibility for either attack; suspicion falls on Sunni Muslims loyal to Saddam Hussein, but because attack is in predominantly Shiite Muslim area, radical Shiites may have been involved; at almost same hour as attack on police, but in Baghdad's richest neighborhood, Jose Antonio Bernal Gomez, deputy intelligence officer at Spanish Embassy, is assassinated at his home after opening his gate to man dressed as Shiite cleric; continuing security problems raise question of how diplomats, United Nations or relief agencies are going to do their jobs in Iraq; photos (M)