Yup
Check with Carnival's website. If I remember correctly, you can use either a passport or your driver's license and a birth certificate. I've taken three cruises with Carnival and I've always used a passport.
If leaving from Florida, Jamaica is accessed by traversing across the Caribbean Sea. If leaving from Texas/Louisiana, you traverse across the Gulf of Mexico and then the Caribbean Sea.
Yes. While you may choose to stay on board, the cruise line may not let you book without a passport. In the event of an emergency (illness, running aground, ship fire) evacuation at any port may be necessary. Disimbarking and embarking would become an issue.
Yes, you need a passport. If you are leaving the USA and going to Mexico then you need a passport.
Yes if you are leaving England then you must have a passport.
Try leaving the country
Whenever leaving the US (and returning) it's always best to have your passport readily available.
Due to the fact that Miami is located in the state of Florida and due to the fact that both Florida and Louisiana are constituent states of the United States, they are both within the same country and therefore you will not encounter passport controls while traveling between them. However, if you are not a United States citizen, you need to have your non-American passport with you at all times.
Only if leaving country
If you are leaving the country you live in, yes.
No. You don't normally need a passport except when entering or leaving a country (There may be countries that require internal passports, but if you live in one, you already know about it.) If you are traveling outside your home country and HAVE a passport, you should always keep it with you in case you need to prove your citizenship, though normally this isn't an issue.
No , you do not need a passport unless you are leaving the US.