I dont think they would kill Black Widow like that but Hawkeye come on he aint getting a movie. Hawkeye has gotten zero buzz I suppose that might change in Age of Ultron but right now yeah not going to happen.
Yeah I think they could survive falling a few hundred feat, and some hot steam. And yes speed feats tend not to be consistent necessarily but it varies based on the character and in naruto fast characters are consistently fast.
Lol be nice to get a feat list from all those heroes in case we have to do this again. Still the question arises is how their durablity because Naruto charcaters can take a beating where as these heroes of olympus seem to be glass cannnons.