Regarding the permits, that's different from state to state, sometimes even counties or cities claim that they have ordinances prohibiting you to land within their limits - how much that would hold up in court is another question (for example: Bethlehem City (PA) does not allow you to land anywhere, unless a firetruck is on scene
I never researched the issue for NY, but in New Jersey ANY landing requires a temporary heliport permit ($10/day I believe) - you can call the State Police about that, they point you in the right direction, who to talk to at the NJ*** (I have actually talked to the sergeant in charge of the aviation unit).
For Pennsylvania state the law is a little iffy, unless you don't land more than "a couple of times", it's ok to land anywhere on private grounds (obviously as long you don't endanger anybody); if you want to go in and out more often, the PENN*** will actually send out a person to survey the landing site, for only $10! This time I talked to the person that comes out if necessary, so he should know
Bottom line: you need to call the state (NYS*** is a good start) and the municipality too... if you want to play it safe also call the State Police; supposedly the fine in the above mentioned Bethlehem City is somewhere around 1,000 bucks!.
Hope this helps!