>>>If I dropped it off in Sorrento how the heck would I return w/luggage to rome?<<<

The Marozzi bus from Sorrento to Rome is one option, but there is only one departure daily except in summer when they have two.

You don't want to drive or pick up a car in Naples at all. I hope you are talking about Naples airport pickup.

For train from Sorrento, you take the local train (Circumvesuviana) to Naples (4€ - about 75 minutes) and change to the fast train (Trenitalia) to Rome (about 70 minutes).