I think you have to wait for the second half of November in order to see the schedule for the second half of December...
If you bought your ticket on-line, it could be quite useful because it allows you to avoid all the queues that you will find in the stations, and in some stations they are really long, especially in the main ones... But a disadvantageous point could be that if your ride is deleted (due to some problems or strikes), you will have to buy another ticket and this could be really unpleasant.. There is a refund but it is lower than the price of the ticket:
http://www.trenitalia.com/cms/v/index.js…
Then another unwanted aspect could be that, if there is a long delay, you will be forced to wait for that train (if you don't want to pay for another ticket) even if there are other trains (which depart earlier) that could be useful to you... Instead if you bought your ticket in the station you could be able to choose the best train for you in that moment...
The problems that I mentioned don't occur so frequently (in fact many people buy their tickets on-line), but sometimes they can occur...