No
Yes
No you dont have to but doing so saves time if you remember that you still have to show the people that you have a ticket before going in
No but buying on line saves time.
It's just like anywhere else. Buy ahead of time to avoid longer lines.
I would recommend purchasing tickets online ahead of time. You can select a specific time for your group to enter. There were people in line purchasing tickets when we arrived so I assume reservations are not a requirement.
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