I arrived at the museum mid-day on this past Friday, 12/8. The only line that I encountered was the coat check. You are issued a pass that is good for the day so I assume leaving and coming back to the museum is not a problem. As the day got later, the exhibits became more crowded. I left at about 4:30 pm and the lobby was fairly crowded but I did not notice substantial lines at the ticket counters.
Yes. You Can Re-enter multiple times on the same day. The lines depend on the day and time you are visiting. Expect 10-15 min wait on a busy day
Tickets are pay your own price. Lines are okay, both people and automatic tickets booths.
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