As a native New Yorker, albeit a resident of Long Island and raised in Westchester, I can tell you that your commute to JFK from Manhattan would be the least of your problems. Simply take the LIRR to Jamaica (Queens) and then get the airtrain to JFK. The issue with living in NYC and Manhattan in particular is whether you could afford to on anything less than legacy widebody pay or perhaps FDX, UPS or ABX. It is rediculously expensive to live in New York. If its a dream of yours, good luck, but I don't recommend it.