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 NJDOT (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 PENNDOT 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 (NYSDOT 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!