Stupid questions for sincere answers ...

1)
A all in 80k
B raise 200k
The rest fold
Dealer kills the hand of A (mixed in the muck while still faces down)
A is out of the turney?
I mean do you really allways apply that?
2)
Idem but the dealer only kills one single card from A hand (I know the answer nut still wanna check if any different answers)
3)
Idem but the dealer only kills one single card from A who still has 2 cards (was playing with 3)
4)
Turn:
A all in 80k
B + C + D call
River:
B bets 200k
C + D fold
A + B must show
C + D can muck
5)
Turn:
A bets 80k
B + C fold
D calls
A muck (retrievable) then realises someone called and wanna take back is hand?