Jambo! Naples is the launch point for Pompeii, the Amalfi Coast and the Capri ferry. Install a JamboSim eSIM before you fly and land already connected.
Airport Wi-Fi is free, but data is what you want for ferry timetables, Circumvesuviana trains and taxi flat rates.
The Alibus shuttle reaches Napoli Centrale in about 15 minutes and the port at Molo Beverello in around 25.
NAP has one compact passenger terminal very close to the city. Local time is CET/CEST.
Yes, your phone joins an Italian network right after landing.
Yes, wherever there is mobile signal.
Install before departure and activate on arrival.