On transport, I live in southern Westchester, and it is an easy 20-25 minute drive to Yankee Stadium, including game day traffic. It's even more convenient to take the direct train, which the MTA runs for Yankee games, but not NYCFC games.
A stadium near Shea would be a longer trip, but not horrible. There would be no public transit option from Westchester/Connecticut - at least not until the LIRR is brought into Grand Central, and even then probably not great. The drive for me would be longer and more subject to traffic issues, but I'd still happily make the trip. It might not be much different for people along the coast and into Connecticut.
A stadium near Shea would be a longer trip, but not horrible. There would be no public transit option from Westchester/Connecticut - at least not until the LIRR is brought into Grand Central, and even then probably not great. The drive for me would be longer and more subject to traffic issues, but I'd still happily make the trip. It might not be much different for people along the coast and into Connecticut.