Industry Items: All product from Touchstone Pictures and Hollywood Pictures will be exclusive to Showtime cable for the next seven years in a new deal signed between Showtime Networks and Walt Disney Studios. . . . Veteran movie producers Ray Stark and Dan Melnick, who have worked together in the past (“Sunshine Boys,” “Goodbye Girl,” “Chapter Two,” “California Suite”) have embarked on a new venture, Rastar/IndieProd, to produce motion pictures and other entertainment projects. . . . Vestron Pictures has formed a $35-million joint venture with Precision Films and Mack-Taylor Productions to co-finance five new films.