About 7000 on average, but let's say 10000 since demand varies. And let's consider doing 10% of them with helicopters. If we average 3 people per helicopter, that's 170 groups in and 170 groups out. If each landing needs 5 minutes of pad time, that's 14 pads. Make it 20 to handle variation.

Wow, that makes it sound significantly more feasible than I would have guessed.

Those are all reasonable questions, but if some entity would be able to answer them, of all things, I think JFK, an airport, would be well equipped to handle them.