Yes
Yes, it's just a bar, although it can get crowded and a seat isn't always available.
No reservations required, but depending on the night it might be a good idea. Also, I might be wrong, but I think a reservation can now easily get you a seat in the balcony overlooking everything. Of course being in the thick of it is pretty awesome too.
Yes, no reservation needed.. though it gets crowded
Yes, I went there recently just by walking in.
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