I need some input from New Yorkers and frequent visitors to NY that dine out.

Im organizing a Wine Dinner in NYC and we will have a fixed menu. We have agreed on a per person charge, which was quoted as $XX+tax+gratuity. Also, there will be a $35 per bottle corkage charge (Im bringing in the wines for this dinner).

So here are my questions....

a) is it customary to charge sales tax on the corkage fee?

b) I assume a 20% tip is standard these days in NY, would I be correct?

c) the last time I went to a BYOB establishment in Manhattan was in 2004, so could you comment on the $35 corkage fee... is this about going market rate?

Of course, if someone has similar experience(s) in other large US cities and would care to contribute here, please do comment... I think its safe to assume that usual practice in Chicago, San Francisco or Los Angeles will be very similar to what happens in New York.

Many thanks,
Alex / Gaucho100K