Welcome to the amazing industry of cruising! I really hope you enjoy your first cruise!
Hurricane paths change frequently, so until then, you can only predict. However, if the hurricane was in fact to hit Bermuda, you sailing would be diverted (most likely to the Western Caribbean).
Very rarely is a cruise canceled entirely. Most of the time they divert, or shorten/lengthen the sailing.
If booked through Carnival, yes. If booked through an outside vendor, check with them for more details; (short answer yes, as most vendors offer a 24-48 hour cancellation policy). On top of that, you would be refunded the taxes and port fees.
When does your cruise leave? Saturday or Sunday? If Saturday, you may be cutting it close as Orlando is 60 miles away from Port Canaveral. If Sunday, you should be more than fine.
Did you insure your trip BEFORE or AFTER Hurricane Humberto? If after, you will not be reimbursed (for whatever you miss, either on or off the ship) as the hurricane is now considered a predicted event.