Getting to Italy: Alitalia, the flagship airline of Italy, has flights to Italy from the US and Canada from most major cities.
You can depart from:
New York (JFK)
Many of the major US Airlines also provide service to Italy, including Continental, Delta and American.
You may also be able to get a good deal on a flight to London, and then from there, use Alitalia, or one of the British airlines to enter into Italy.
There are some other airlines that operate within Europe (Air Europe, Volare Airlines, Meridiana, Lufthansa, etc). These airlines also have flights to Italy. Many of these airlines are on Expedia.com...check them out for to see if they have any special airfares. October through March is when you will find the lowest fares, except for the two weeks around Christmas.
US and Canadian citizens will need a valid passport for entry into any of the European Union countries.
This will allow you to stay in the country for a period of up to 90 days.
After that, you will need to apply for an extension or secure a visa.