The drive from Rome apt or down town to Positano, Sorrento or any other town along the amalfi coast is a little longer then 3 hrs drive and most of it is on the main highway A1 except the very last part of it that is along the famous Amalfi coast.
Driving on the highway you can stop for bathroom or drinks at anytime you wish, rest areas are located every 20 minutes.
Your English speaking driver will point out the most important site as the famous Abbey of Monte Cassino that was destroyed by the allied troops in February 1943 and then completely rebuilt after the war.