Rome: Where can I find a beauty store in Rome?
There is a Sephora on Via del Corso. For cheap profits, try the Despar supermarket by Campo de' Fiori, or the Punto at Largo di Torre Argentina. For an affordable makeup store with some hair products, IT Style...
Florence: Where can I buy the Harry Potter Books in Italian?
A large chain bookstore with the best selection is la Feltrinelli Librerie. You can also order them on Amazon.Or if you have time for them to be shipped to your hotel!
Rome: Where to go for local food in Rome?
Get a bit outside of the historic center and try Flavio al Velavevodetto in Monte Testaccio or Da Cesare in Casaletto.