A few helpful ideas
Buongiorno,
Driving a car is always an interesting point, it really comes down to how much you enjoy driving. The time period you have selected will have the roads pretty clear, so you won't have a lot of competition on the road
Are you looking to position yourself in one place and then move about? That could make it easier if you are driving on your own. That way you will quickly become familiar with the roads and landscape. I particularly like Castellina or Radda in Chianti
Check out some of these suggestions:
http://www.tuscanyaccommodation.com/castellina-in-chianti/
From here you could do several one day tours (driving about 1 hour) Siena, San Gimignano, Florence, Arezzo, or Buonconvento.
As for your culinary style, I believe you will find that every restaurant has a list of "contorni" (vegetables) as well as several pasta options that don't include meat (niente carne...no meat!) In fact, Florence has quite a few of lovely vegetarian restaurants:
https://www.visitflorence.com/eatin...rence/vegetarian-restaurants-in-florence.html
Some of my favorite dishes include ravioli di verdure with butter and sage, pasta with mushrooms, rice with vegetable. They also eat a lot of dishes with white beans (excellent with extra virgin olive oil). As well as lots of fresh veggies. There is always cheese on the menu, and you could try for a sunny-side-up salad with shaved truffles on top....perfect for the season.
Buon Viaggio,
Donna Denise