Not that I am aware of... You would need a car to get to Siena, unless you are in the mood for a good biking trip. There may be restaurants at some of the inns around the area.
The restaurant at Borgo Scopeto is superb, by the way.
The hotel's restaurant is very good, other good ones will be 10-15 mins driving.
Not within walking distance. You need to hire a car or call a taxi (hard to find).
There is a good restaurant in the hotel. The vineyard is also worth a visit. But like Sienna this is a taxi ride away.
There is one restaurant on site and it is excellent. While we were touring one of the villages, we stopped at a local meat and cheese shop and purchased some items for a couple of meals.
I would not let this deter you from booking this hotel.
Get an answer from Borgo Scopeto Relais staff and past guests.