Hello, what other cities are you planning to visit? I highly recommend visiting Varenna, you must see the "milk river" Fiumellatta, this is the shortest river in Italy, its length is only 250 meters. Answering about lake Como taxis, personally I have always used gettransfer, they work throughout the country, and can take you comfortably to any destination. By the way, behind Lake Como, on its shore is Villa del Balbianello, this is an amazing place built in the 18th century, it was originally called Villa Arcimboldi, by the name of the family to which it belonged.