While Pompeii is impressive it is big and a lot of walking is required. Herculaneum is smaller, better preserved and quieter in my experience.
You be better off taking him there. We always walk from the train station but I'm sure you'll be able to park near.
Not sure about organises holidays but it is simple to sort yourself. Fly into Naples and get the train or bus. I would stay in Sorrento, easy access and beautiful. Cars not the easiest on the Amalfi coast and if you’re staying on the north side public transport seems pretty good.