You did not mention the time of year for your travel. In the fall and winter months the sun sets 4:30-5:30pm. It's not until late spring and summer when you can rely on the sun being out in the evening. Enjoy Rome!

Christmas eve mass is at 9:30pm on December 24, 2019, I would follow the instructions in the letter.

There is a train from Florence to Pisa. Not sure what you want to see in Florence but there is a lot to do. Pisa can be done in one dAy.

We self toured Pompeii, found the train into Naples quick and efficient from Pompeii, and went to the Scavi site early, and bought tickets without trouble and straight in. BUT that was very early spring! It is a big site, and when the crowds started to arrive, it became difficult to traverse all the available ruins. TAKE water!!!!

If you’re not on a tour, take train from Rome to Pisa. Did a skip the line tour for Coliseum and Pompeii as well as Vatican bus picked us up at hotel.

I think it is a perfect time to visit. Amount of time to spend depends on how caught up you get when viewing these incredible sites. I could spend days there.

pompeii is 15 euro and free under 18.