Yup, but the 'Secret Bombing' stopped before the Case-Church amendment went into effect.
I've seen sources that say that ARVN surrendered stockpiles of ammunition to North Vietnam and other that say there wasn't any.
The Vietnamese did use captured F-5's against the Chinese in 79' so there were enough spares apparently to keep them running at least for that long.
The US sacrificed great amounts of blood and treasure trying to prevent the takeover by the communists. North Vietnam blatantly violated the Paris Peace Accords, but the US did not fulfill the promises it made to South Vietnam to protect them against these violations. The Democrats in Congress sought a political advantage by becoming the anti-war party after they were the ones (JFK and LBJ) who got us involved in the first place. And the Americans fighting the war, 75% of whom were volunteers like me, were demonized and castigated as killers and war criminals. It took the US military decades to regain its respect and standing in the society.
The South Vietnamese continued fighting after we left. They were slowly starved of resources and left adrift by the political leadership of this country. We won the war militarily and lost it politically. Korea was a draw, but Vietnam was deemed a loss, the first in our history. We have seen the same thing happening in Iraq and Afghanistan. The sacrifice of our troops is being squandered away again. At some point, it will become difficult to recruit people into the military. As Kerry (the traitor) said, "How do you ask a man to be the last man to die for a mistake?"