Yes, you need a passport card to go to Jamaica. You can get these at any USPS and have your picture taken at drug stores.
Can a US citizen use a passport card to fly to Jamaica by air
yes
YES you can, you just cant leave the Jamaica with it expired
No, you can visit Jamaica up to 90 days on your Italian passport.
Yes, and Jamaica doesn't require Brits to get a visa.
No. You can also use your credit card.
No. You must have passport if you are flying there. If you are going by boat, then an enhanced drivers license (EDL) or a US passport card is sufficient.
yes
no a passport
None - you need a passport. A Green Card is not a substitute for a passport.
Only if you intend to get off the ship.
You probably have to go to the consulate of Jamaica in wherever you are in Canada.
As you told that if you are living in Jamaica than there is no need of passport but if you belongs to other country than you have to take passport for going there. Yes you do need a passport to enter the country