Flying from ORD to NCE via FCO with a 1:00 layover. Will that be enough time to go through customs/immigration and make the flight to Nice? Is there anyway to speed through immigration at Rome?
If your luggage is checked through to Nice (or if you only have carryon) that will save you time. Then you will only have to go through immigration (passport control).
Normally, www.adr.it (Aeroporti di Roma) has a lot of information about Fiumicino (Leonardo da Vinci) airport, including gates and terminals for arrival and departure, and maps, so that you can see how far you have to go. It will be a lot easier if you don't have to change terminals. However, right now, with the volcano problems, the website is experiencing overload.