"Licensed" means a business license issued by the city you are doing business in. "Insured" should mean the painter has general liability insurance to protect the business and the homeowner. The cheapest, bare minimum coverage is rarely a good move for either party. Some contractors believe that having car insurance entitles them to say they have "insurance". Ask for (and get) a certificate of insurance issued for your specific address.
Painted storm windows "disappear", enhancing the look of the window rather than covering it up. This is particularily striking when the storms and sashes are painted to complement the window trim.