court coverage

Need some help on some court coverage/primary situations:

1) Ball is in the backcourt and new trail is administering the throw-in with pressure. trail/new lead is at the center stripe moving with the flow towards the other basket. If the ball comes quickly to the new leads side in the backcourt, and a foul is committed, who has primary? Does the new lead also have the sideline on his/her side all the way to the baseline?

2) Also, in the frontcourt with the ball above free-throw line extended, the trail has primary even on the leads side of the court, however the lead has the sideline all the way to center court. If you are responsible for that sideline as the lead, how can you not keep on eye on the ball action in order to determine who the ball went out on?

comments?