Mike,
Good examples of two situations that, hopefully are not to common, but need to be addressed. My answer to both situations is the same. If the dealer failed to hear or recognize the raise, and the raiser failed to stop the dealer from burning and turning, Player B's wager can only be recognized as a call.
Mike, I will assume you meant to write Player B instead of Player A here: "If it were reversed, and after the flop Player A (B) claims he didn't say all-in, would he be forced all-in despite dealer not hearing it and nobody speaking up before the flop?"