There's plenty of fuel available but most stations are pretty small and have limited hours. If you are willing to pay even more than the already very expensive prices and buy it at service stations on the autostrada the hours are much more flexible.
Most small places the attendant pumps for you. I've never heard of tipping for that. Do you do that where you are from?
Some pumps at bigger places and out-of-hours are card only pump it yourself. Most US swipe only cards won't work in that situation but they will during the hours the station is attended and you can take your card inside and swipe it. It is usually easier to pay cash.
It is easy to find fuel if you have a decent Garmin or Tom Tom GPS.
Fuel is around €1.70 per litre, more for unleaded, a tiny bit less for diesel. That works out at around US$8.80 per US gallon.
Be very careful about pumping yourself - in Europe a black nozzle means diesel which often comes in at least 2 grades, unleaded will probably be in a green hose and nozzle. in at least 2 grades.
Each driver in Italy will need a mandatory IDP along with their home DL, and watch out for the dreaded ZTLs. Have plenty of money for the tolls, and stick to the speed limit even if the locals don't. They know where the hidden cameras are. Make sure you take the mandatory insurance coverage. If you drive into Switzerland of Austria you must have the mandatory vignettes.