Was last in Italy in 2013. Italian Cycling Center for nearly two weeks. Setting was a small town outside of Bassano de Grappa in the Veneto region. Evening dress is generally casual, but I would bring at least one shirt with a collar. We had no reservations about stopping at cafes and restaurants for lunch/snacks in our cycling clothes. We even stopped at this one posh villa in Prosecco grape country. In one hallway there were photos of actress Sandra Bullock. She stayed there when visiting the area.
One of the fun parts about visiting Venice is wandering around on your own. Get a good guide book and decide what you want to see. When I was there again 2013 the GF (who had never been) and I took the vaporetta (boat bus) to the far end of the main island and meandered are way back to the train station. A guy who was at the Cycling Center and who usually rented a place there every summer recommended this place for lunch: Cą D'Oro alla Vedova. There is no web site, but you can find the address on Google Maps. It's at the end of a small alley. Hard to find, but worth it. The food was terrific. Thanks to sites like Trip Advisor, it has become popular with tourists, but a lot of local business people still go there for lunch. The pasta with sauce made with squid ink was divine and not something you will find many places. The calves liver with polenta was also terrific.
Wear long pants if you plan to visit churches. And I would bring a rain jacket.
Italian drivers may seem crazy, but most of them are highly skilled. (It's harder to get a license there than in the states.) Our host explained that drivers will expect you to follow the rules of the road. Things like yielding to vehicles that are already in roundabouts. Ride smartly and you shouldn't have any problems. I don't now about Tuscany, but where we were there we countless cyclists. Sunday is the big group ride day.