Sorry, the salad is not included on the DDP. You can order it, but you'll have to pay OOP (it has it's own price point). VN does have complementary bread service (a few slices of bread, nothing really exciting) that you must ask for if you want it.
I would ask at VN before ordering the salad and assuming that it can in place of the appetizer on the DxDP. When I was there last, the server was very clear that only the items under Picooli Piatti, Antipasti, and Fritto Misto (takes two people) were eligible.
There are two categories of salads, the first are the Insalate, which are listed below Pasta. These are basically entree salads and would not count as an appetizer. You might be able to order them as an entree. There is also the "Family Style" House Salad, which is listed under the pizzas. I doubt this can be ordered as part of the DxDP, but I would ask the server to see if it's eligible. It says that a minimum of two people must order it, so my guess is that it would take at least two people on the DxDP to order it (like the Fritto Misto).