No clue (although I know Harleys are made in York). I was hired a few months before New York gave me an offer and I turned it down with that hope in mind. Neat small job, lots of history in the firehouses, decent fire duty and I'm a big fan of their new engines.
No, in normal operations they draw thier mutual aid from the career departments in the neighboring New Jersey municipalities and then draw from further into the state. I believe Newark was on one of their fires in some capacity a few years ago.
I'd guess it's not quite a dramatic drop, but more so a gradual drop as your cross the borders. Most likely having to do with density, socioeconomic status, zoning, etc. But, like you I have no hard numbers to back this up.
Yes and no... Proportionally most departments respond to many more EMS runs than FDNY suppression. Most departments are sending companies to all EMS runs where they'll initial patient contact, stop the clock and then potentially wait hours for a EMS transport unit to be available. Of course FDNY...