Mostly I see blown in insulation which is nice because you can cover the joists and get a much higher r-value - ie r-60 and even above. I can't remember if that is a problem in NY - I wouldn't think so. Lowe's rents you a machine to blow for free. You would remove the old insulation - just because it may be moldy and it isn't doing much anyway.

The vapor barrier question is a big one so you need to be sure on that. I am 90% sure you would be fine but I'd want to be sure.

Don't use poly on the ceiling for any reason. It is a bad idea.

Here is a link that might be useful: Corbett Cooling

Why is poly bad? I see it being used on many home shows?

friend had his blown/batt attic insulation removed and than put down a layer of spray foam and had cellulose blown on top. says 2nd floor is much warmer now. he had areas that had drafts and leaks before and wanted a tight leak free install.