A1 has been fouled on a shot attempt (two or three). On the first free throw there is a double lane violation. The shot is taken away but then what. Shoot the other(s) and then use the arrow or just take away the shot. If the shot is all that is taken away then the non-shooting team gains advantage.

You simply take away the point if the FT scored and continue with the next shot.

The violation by A causes the ball to become dead immediately. Even though A and B step into the lane together, cancel that shot and resume play.There is really no advantage to team B here. If the violation is on the 2nd (or 3rd) shot, cancel it, then use alternating posession.

The ball does not become dead immediately if B enters the lane before the ball hits the rim. But it does if A enters the lane too soon, ruling is to disregard the throw and go to the next one. If that throw is once again violated by both teams then A entering the lane caused the ball to become dead immediatley so its a violation on A and B gets the oob. You would'nt go to the arrow here because its a simple lane violation.