A link that will help you tremendously in finding hotels based upon type of accomodations (3,4 or 5 star example) as well as "where" (example: walking distance to the train station) are available on a website that my husband and I used to book our first Italian trip. It also allows you to view the hotel online. Venere.com.
We stayed at the Virgilio which was about 3 blocks from the termini.
We also took a high speed train to Naples. The Naples main train terminal is about 3 to 4 blocks from the port but, beware. We have never seen such crazy driving in our lives
You might want to rent a taxi at the Naples train station to take you to the port.
Also, one more piece that you might want to watch. Taxi's. Like NYC there are real taxi's and there are the ones that are standing at the door waiting for tourists that are incredibly accomodating but, they charge you 5 to 10 times more to get you where you need to go. Just like in the states both in Rome and in Naples there are taxi areas where you can catch a "real" taxi that will not gouge you on the price of a short ride!
I think you will like the venere website and what it has to offer. Have a great trip.