I always make a reservation if at all possible. I've often been disappointed if I don't and just decide to drop-in. They will likely be able to seat you eventually but it may be an hour or more. Even the bar seats are usually full.
Reservations aren't a necessity, but highly recommended, especially if you want a specific seat or are going on even a mostly busy night.
I don't think so, as a rule, but call ahead to check on crowding. Certain days/weekends/weeks in a college town are very busy.
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