Hi Diane and welcome to our community! I'm not sure how long it generally takes to get through customs in Naples, because I've never flown through that airport. Perhaps someone else here in the community has more information.
As far as where to meet your driver, you should ask your hotel. Generally speaking there is only one exit where passengers can come out of the terminal into the main waiting area of the airport, so if you exit with the other passengers, most likely your driver will be waiting for you holding a sign with your name along with other drivers waiting for passengers as soon as you exit the secure area of the arrivals terminal.