We cruised the western half of Cuba from Cayo Largo to Havana for 7 weeks in February, March and early April 2017. It had been a dream and was an interesting experience.
Restrictions at Ports of Entry and in finding food other than lobsters were balanced by empty anchorages and learning about communist life. It was expensive in Havana if you eat in the state owned restaurants and hotels but worth it to see the city, museums and ride in an old American car. The Casa Particulares (bed & breakfast) and Paladares are great value for a home cooked meal.
Take all the food and household items you can carry. Plenty of US dollars will help pay all the Customs fees if they don’t use a credit card machine. Changing dollars into CUC is easy in some ports but don’t rely on it, nor on the availability of working ATMs outside the main towns.