Advice: Good Resources for Sailing from Gulf Coast to Rio Dulce

[Elletrue]

I need to get a 22 foot sailboat from the US to the Rio Dulce. When is the safest time of year to deal with the northerly current between Central Am. And Cuba? Which routes are the safest? What is the best route? When are currents, wind directions, weather the safest to move a small sailboat south? I could leave from Florida or any location along the GOM. What are the best resources for planning that trip.

What Docs do I need for entering other countries other than passport? I read somewhere about some other document that should be acquired before leaving the States.