Hi CoreySilver,
In the order that you gave this is how I would handle each infraction:
"Ill double you up" although has not committed to calling has made unclear statements that are unethical, depending on what he does he will receive a penalty after the hand is complete, for example if he goes on to call, knocking the player out, I would give a big enough penalty that he does not benefit from the all-in call.
400/800 Man has done nothing wrong, I don't see any real issue with what he has done, and will allow the 3000 to stand as the bet, I don't feel a penalty is justified, however may instruct the player to use plain english, and ensure his verbal declarations are clear and to the point in future.
"You can have it" this is a pretty awful one, from the sounds of things a blatant angle shot, and I know whatever I say on this one is going to be argued either way, here are my considerations:
Player B has made a gesture to concede the pot, releasing his hand, although not making a forward motion with his hand in a face down manner, which would simplify this, as a forward motion that illicits a re-action from another player is binding in my book, there is also the consideration that B has made a motion releasing his cards, conceding the pot and by not calling the all-in from player A.
Player A has irrevocably mucked his hand, without waiting for the pot to be awarded, nor for the other players hand to be irrevocably mucked.
There are therefore faults on both sides, player A for not waiting and player B for his angling/query yielding of the pot. As I am typing this I am swayed both ways tbh, should I award the pot to A or B, I think for me it would come down to what everyone at the table thought of player B's actions, was the majority satisfied that player B has conceded the pot?? if they were I would give the pot to A, if they were not I would give the pot to B, that really is a judgement call for me, ensuring I listen to everyone's 'piece' at the table of what they considered the intent to be.
EDIT<I didn't edit my earlier typing but the more I consider the 3rd the more I am leaning towards player A still getting the pot, for a whole multitude of reasons, which I have already typed above as considerations.>
Regards
Stuart