Get a SIM card. TIM is a wireless provider that sells 1 month SIM cards: https://www.tim.it/fisso-e-mobile/estero/tim-tourist There is a TIM shop in the Rome airport and at the Rome train station Rome Termini.
Italy is a much more cash-based economy than the US so plan to use cash at small shops and more suburban/rural areas. However do not carry more than a few hundred Euros in cash at any one time. You can get cash from ATMs using US debit cards, some banks do this for free but most charge fees. If you are in a touristy place, they probably accept credit cards. Check with your bank to see what international fees that you may have to pay to use your debit or credit card. Also make sure to put a travel notice on your card or you bank may lock your card for fraud protection.
One of them isn't a toilet! Bidets are very common in southern Italy so give it a try.
The answer is: get a snack! Restaurant don’t open before 12pm for lunch or 7pm for dinner. In touristy places you may find restaurants open all day. Italians go usually out for dinner around 8.30/9 pm or later.
Ambulance: 118 Police: 113 Carabinieri (another type of police): 112