Concerning the last section about refunds...

Does that mean that the cruise line could drop you at ANY port (or any rock in the sea) and expect you to pay your own way to where ever you were headed?

My suggestion to Costa would be to be fairly liberal in their settlements. They have severely damaged their reputation and if they nickel and dime the passengers, they might find themselves out of business. Nobody would ever take a chance on them getting to their planned destination.