I am traveling to Italy in two weeks via Bergamo airport and after that I am supposed to go to Milan train station because I will go to Catania, first what is the best transportation from Bergamo airport to "Milano Centrale" and how much does it cost, secondly what is the best train to Catania and The cost of the ticket? Is it possible to book a few hours before departure from the ticket office at the station, or do I have to book a day before because I will not be able to do that?!