Preheat the oven to 475°. Rinse the turkey inside and out and pat dry. Season the cavity with salt and pepper and set the bird on a rack in a roasting pan large enough to let air circulate all around. Rub the softened butter over the breast and legs and season with salt and pepper. Roast the turkey in the top third of the oven for about 30 minutes, or until beginning to brown. Reduce the oven temperature to 375°, cover the turkey loosely with foil and continue roasting, basting often, for about 1 1/2 hours, or until an instant-read thermometer inserted into the thickest part of the thigh registers 175°. Transfer the turkey to a serving platter, cover again with foil, and let stand for at least 20 minutes before carving.
Meanwhile, cut the turkey neck and gizzard in half. Heat the vegetable oil in a medium saucepan and add the neck, gizzard, heart and wing tips. Cook over moderately high heat, stirring occasionally, until browned and crisp, about 7 minutes. Stir in the onion and celery and cook until golden. Add the wine and boil until reduced by half, about 7 minutes. Add the chicken broth and bring to a boil. Stir in the tomatoes, parsley, thyme and bay leaf and cook over very low heat until reduced to 3 1/2 cups, about 1 hour. Strain the turkey stock into a bowl; reserve 1 1/2 cups for the stuffing.
In a small bowl, mix the water with the flour until smooth. Remove the rack from the roasting pan and spoon off the fat. Set the pan over 2 burners on high heat. Add the remaining 2 cups of turkey stock and bring to a boil, scraping up any browned bits from the bottom of the roasting pan. Whisk in the flour paste and cook until the gravy thickens, then add the port. Strain the gravy into a sauceboat. Carve the turkey and serve with the gravy and Sausage-Apple Stuffing.