Naples ArteCard-3 days or 7?

Am assuming you are coming from the Naples airport. Yes, the Alibus takes you to Naple for E3 Both the train station and the port area. Yes, it's included in the Arte card however you need to purchase online to use this. As of last oct. there was no place to purchase at the airport. Only at the train station and some of the museums. The 3 day covers 3 sites and all transportation in the area: bus,metro, circumvesuvian, bus along the amalfi and the vesuvian bus from Pompeii.
The bus to Vesuvius is a new company and I don't know if they stop in Herculaneum. There may be 2 runs from there. The 7 day gets you into 5 sites but does not include transportation. There is a 3 day transportation pass for E20. But at this point you would probably be better off buying 2/3 day passes. That would give you 6 free sites and 6 days of transport for E4 more. To figure out if it would save $$$,scroll to the bottom of the arte card site. click on the sites you would want to visit,then scroll down and it gives you Hrs. open, cost of reg. ticket, and the easiest transportation option to get there. If you have the time, an amazing place is Reggia Caserta It would probably take 6 hours to do it justice. If you don't have time for this at least spend a few hrs. in Palazzo Royale.

sorry, the 2day covers 2 sites reduced for others and trans. So 2/ 3day would give you 4 free + trans. for 6 days