Short answers, pulled from the story.
The Gulf of Tonkin Resolution authorized President Lyndon B. Johnson to use conventional military force in Southeast Asia without a formal declaration of war by Congress. It allowed him to take "all necessary measures" to assist any member or protocol state of the Southeast Asia Collective Defense Treaty, including involving armed forces.
The House of Representatives passed the Gulf of Tonkin Resolution by a vote of 416 to 0 on the 10th of August 1964. The Senate approved it 88 to 2, with only Senators Wayne Morse of Oregon and Ernest Gruening of Alaska voting against it.
A declassified 2005 National Security Agency historical study concluded that no attack occurred on the 4th of August 1964. Captain John Herrick of the USS Maddox reported shortly after the alleged incident that the "torpedo boats" were almost certainly radar blips caused by freak weather effects, and that no sailor aboard either destroyer had actually seen a North Vietnamese vessel.
Senators Wayne Morse of Oregon and Ernest Gruening of Alaska cast the only two nay votes. Morse warned at the time that the resolution was "a historic mistake" and predicted that those who voted for it "will live to regret it." Gruening declared "all Vietnam is not worth the life of a single American boy."
Fulbright supported the resolution because President Johnson personally assured him it would not be used to start a ground war and was intended only as an election-year signal to intimidate North Vietnam. Johnson also hinted he might appoint Fulbright Secretary of State after the 1964 election. Fulbright later said he believed Johnson when told the resolution "was not going to be used for anything other than the Tonkin Gulf incident itself."
Operation 34A was a covert program begun in January 1964 in which U.S.-trained South Vietnamese commandos conducted maritime raids on coastal North Vietnam under American naval operational command. The raids on North Vietnamese radar stations on the nights of July 30 and 31, 1964, preceded the Gulf of Tonkin incidents, but Defense Secretary McNamara testified falsely before Congress that the USS Maddox had no connection to any South Vietnamese patrol boat activity.