If the QB has the ball and throws it to another receiver behind the line of scrimmage. If after he throws it his flag gets pulled... can the receiver throw it back to the QB and the QB can still throw or run until he is two hand touched by the defense (since he only has one flag) or will the ball be down where the QB caught the ball?

down where he caught it.

negative ghost rider, he needs to be touched

bundy had it right...a player without a flag or flags is down when he touches the ball

for real, needs to be touched? what league are you playing in?