-The size of Manhattan, however 1/3 of the City is quarantined. Basically that part is No Man's Land.
-They are zombies. They cannot reproduce with themselves, they need a human host to spread the virus.
-As I mentioned, the area is surrounded by harmful energy shields, so it's very unlikely your character has explored it. However, if he possesses a particular set of powers, he just might have. That is up to you.
-As I said, there's no way your average joe can jump over the energy shields.
-Yes, they will. The drones are designed to shoot anybody who has been infected by the virus.
-Yes, our characters will be immune to zombies.