Stay in Sorrento as a home base, a nice safe town which is better than staying in Naples. There are lots of tours available through Get Your Guide of the Amalfi coast, Pompeii and Capri. You also just take a ferry from Sorrento to Capri and tour on your own.
Take the Sita municipal bus line from Sorrento to Amalfi coast. According to a Rick Steves guest the bus tickets can be bought at convenience/tobacco stores. There is also a ferry that takes about 40 minutes - use the Omio website or app to book.
You can buy bus tickets at kiosks or at convenience stores.
From an Amalfi forum: "As you get out of the Sorrento train station, after you go down the
stairs, there’s a kiosk from where you can also buy SITA bus tickets.
You’ll need the AC4 (€ 2.90) for Sorrento-Amalfi and AC1 (€ 1.30) for
Amalfi-Maiori. The bus station is another 20-30 meters distance from
there. The SITA bus company publishes a list of all the places you can purchase tickets from: www.sitasudtrasporti.it/agenzie (select ‘Campania’ if prompted to choose a region). You can also further filter out the list by entering the Comune (city/town)."
Probably best to hire a guided tour of Pompeii.
Visit the Saint Michael church on Capri for is huge mosaic floor tile.
Pastum is a bit farther from the Sorrento area - check for buses.
