We are ending a RS tour in Florence but flying home from Rome the next day. We are 6 people. I have accommodations near the termini. Should I book this travel in advance? How do I go about it?
If you are sure of your date you can purchase in advance for some pretty good discounts
Station names;
Firenze SM Novella
Roma Termini
Trenitalia
https://www.trenitalia.com/content/tcom/en.html
Also check ItaloTreno
https://www.italotreno.com/en
Both run multiple fast trains thru the day
Choose a direct ( no changes) fast train (Freccia)
Firenze Santa Maria Novella is the name of the main station in Florence.
Discounted tickets have strict restrictions on your ability to get a refund or make changes, so you must be certain of your plans. Once a seat on a specific train is booked, you are locked on that choice.
There's endless number of trains running between Florence and Rome.
You can purchase in advance if that gives you any peace of mind or, buy them at a kiosk when you get to Florence or, the day of travel.
Arriving at Rome Termini, than walking over to catch the Leonardo train to FCO should be a breeze.