NYE/Driving in Italy

If there is the possibility of snow I would expect the rental car co. to provide chains.

If there is a likelihood of snow, a more expensive car is the last thing I would want

I cannot help you on New Year Eve activities.
You can catch a cab over to Hertz on Sansovino to rent a car. It's about 2 miles from the Florence train station, and rentals there don't come with the taxes and surcharges placed on all car rentals at airports.
Chains wouldn't be required that far south for winter, and most hilltowns are south and southwest of Florence.
A Golf is a mid size car in Italy--in comparison with Fiat 500's and Smartcars. It's plenty sufficient.
The most popular place to turn in rental cars is at Orvieto's Hertz location--across the street from the train station. It is 70 minutes by a regional train into Rome Termini. Orvieto is about 90 minutes by 4 lane and great toll roads south of Siena.

Regarding number 2 - have you studied and become familiar with the idiosyncrasies of Italian driving law?

To save the hassle of telling you what you already know, I'll just bullet point - if there is one you don't know or don't understand, just ask and we can clarify:

• National Speed Limit

• Speeds in towns and villages and where they apply

• TUTOR

• IDP

• ZTL

• Insurance

• Street markings and the significance of different colours

• Fuel pump colours

• Fuel station hours

• Fuel station payment

• Bus lanes

1. Florence is a metro area of 1.5 million people with about 30 universities and approximately 60,000 university students, in addition to the 10 million tourists visiting every year, therefore there will be plenty to choose from. I will give you some websites where you can check on events for NYE in Florence. Use Google if the English option is not available. You can search more using the key word CAPODANNO (NYE).

https://www.capodannofirenze.it
https://www.firenzenotte.it/articoli/capodanno-firenze/
https://www.studentville.it/divertirsi/passare-capodanno-italia-2018-citta-ed-eventi/
https://www.visitflorence.com/florence-events/
http://www.theflorentine.net/events/
https://www.gogofirenze.it/eventi/oggi.html
http://www.firenzetoday.it/eventi/

2.
In spite of what some commenters above wrote, snow is very common in Tuscany in winter, even at low altitudes. As a matter of fact there are several ski resorts in the region.

In fact it pretty much snows every year, multiple times a year, at practically all locations above 2000ft (600mt) in altitude, and even Florence, which is very low in altitude (170ft, or 50mt above sea level) sees snowfall, albeit it doesn’t always stick to the ground, except for the hills like Piazzale Michelangelo, and when it does it is rarely more than an inch or two. But every few years even Florence gets a significant snowfall of several inches to over one foot. Last snowfall in Florence was in March 2018 (about 1 inch). Last significan snowfall in Florence was in December 2010, with about 8-10 inches. The record snowfall in my lifetime in Florence was probably the famous January 1985 when the Arno river froze. 45 cm of snow (18 inches) covered Florence then.

Below some photos of Florence under a white blanket.
https://goo.gl/images/VbGw9F.

As a result it is MANDATORY TO CARRY CHAINS OR SNOW TIRES on NEARLY ALL roads of Tuscany between Nov 15 and April 15.

That includes the entire A1 Freeway from Bologna to Arezzo, the entire freeway from Florence to Siena, and the entire freeway Siena-Bettolle-Perugia.