For Fast Lane, I believe that would only be good during the regular operating day (10am-5pm). Although if this fall is the same as previous, you won't need it on the weekends during Haunt. The park is very quiet.
You will probably have to buy the separate "Fright Lane" during the Haunt event. I'm guessing it will provide access to the mazes and the rides. I will try to confirm with the park and update you all when I hear back