I think, personally, you should add 2 teaspoons, or even the zest of a whole lemon. It really adds a great tang to the ziti without being overpowering. For a baking pan, I would suggest you bake this recipe in a 9x13 pan because there is a large mass of food in this recipe; tasty food though :)
Enjoy this recipe because it is absolutely delicious! We ate it all!