WASHINGTON (AP) — The House overwhelmingly passed a resolution Friday that would bar President Barack Obama from sending forces to Iraq in a "sustained combat role" without congressional approval, a bill likely to have greater symbolic than legal effect. [...] it risks opening up several questions related to the Constitution's separation of powers between executive and legislative branches, even if Obama and his top military advisers already have ruled out sending combat troops to help Iraq fight extremist insurgents. American service members also are involved in improving U.S.