In terms of flavor and texture zucca Napoletana resembles the butternut squash that's sold in North America.
Because of its size zucca Napoletana is sold by the slice. When choosing to buy a slice, if you are in a market where the vender is selling slices from a squash (like here), ask the vendor to tap it -- it should sound firm. Also, make certain that the skin of the squash is firm and blemish free, and examine the cut end. It should be moist, and look firm. If it looks slick, there's something amiss. Likewise, if it looks dry (or even leathery) there's something amiss.
A slice will keep for a couple of days in the refrigerator, but you won't want to keep it for longer. Come time to use it, peel it, dice the flesh, and proceed with the recipe.
A few Italian recipes with squash:
Confettura di Zucca, Squash Jam: Perfect with cheese!
Yellow Squash Minestrone
Old-Style Versilian Sbroscia, a Squash and Bean Soup
Tortelli di Zucca, Mantova's signature dish
Risotto alla Zucca, Squash Risotto
More about Squash and other recipes
Squash Elsewhere On About:
Delicious Squashed Apples
Apple and Roasted Butternut Squash Soup
Creamed Butternut and Apple Soup
Roasted Butternut Squash Purée
Winter Squash with Horseradish
Butternut Squash Pie