does putting a car in neutral while accelerator is stuck blows the engine?

It depends. Most cars have electronic rev limiters installed that cut the fuel off before red line, and most will limit engine revs to significantly below redline when in Park or Neutral.

However, there are old cars that don't have rev limiters and some foreign cars (VWs come to mind) that don't have rev limiters at all. If the engine goes above red line for any appreciable time the engine will blow. But turning it off if the accelerator is stuck is a good way to avoid that.

it has the fast potential of doing so. if it is in gear and the accelerator is stuck, and then you take it out of gear, that then allows the engine to rev to it's max, or at the limiter

Yes

it depends on how fast it,s idling. i doubt it because it runs faster on the road then sitting fast idle.