We've just joined this forum, so the info may be a bit too late for you, but might be useful for anyone in your wake. We are British and sailed our UK registered yacht from Curacao to Cuba in December 2006.
Visas - we were issued a 30 day visa on arrival, and were able to apply for a 30 day extension.
Currency - don't take US dollars - you get a terible exchange rate and also pay a hefty commission. We exchanged both Euros and ££ for a decent rate.
We arrived in Santiago de Cuba, where the check in process was lengthy and involved around 10 officials. Sounds bad?? Actually it was very pleasant - all the officials were courteous and interested in us and our travels, and all the form filling was done by them. Officials in many Caribbean countries could take lessons in "customer service" from those guys.
You will hear much about the "burden" of checking in and out of each harbour. Yes, you are visited by officials in each harbour, but again we found them to be friendly and efficient. It was a good way to meet the locals! Once out in remote areas such as the Jardin de la Reina, there were no officials, just friendly fishermen.
We wouldn't hesitate to return to Cuba. If you'd like more info, our website is now on the Cruiser Log listing
as sv Do It
, and we have a section in the Logs about Cuba.
Hope you made it to Cuba.
Ruth & Angus