I've just returned today (Tuesday) from the April Walking in Tuscany trip.
I would recommend walking boots as some of the tracks are quite stoney. They are also pretty steep in places. Trainers better for the day trips to Florence etc. in my opinion, but some of our group did use quite light weight footwear for the walks.
The hotel is good but pretty far away from anywhere - the staff were very friendly and the food was good. The views from the hotel are fantastic, especially when the mountains were snowcapped on Monday morning.
Take a waterproof - we got wet (very wet last Sunday) several times, you may be lucky as its later in the season and it may well be hot and dry.