NNE is the direction you would fly.
Only certain people are allowed to travel to Cuba, I know of professors, religious and humanitarian organizations. Since Puerto Rico belongs to the U.S. the embargo is enforced here too. Because no airplane flies from San Juan to Cuba, most people who go there usually take a flight to some Central or South American country like Panama and then fly to Cuba from there.
around 6 hours
North West
South
7000 miles
the last time people to fly to cuba was in 1987 if my calculations are correct
From Caracas to Brasilia, a bird would have to fly South East
by plane.
A flight from the UK to Cuba will generally fly west towards Ireland, then over the Atlantic to Cuba or if it were flying from London to Cuba, it would fly along the south coast of England towards Devon and Cornwall and then directly over the Atlantic towards Cuba.
There are millions of planes that fly over Cuba on a daily basics. There is to many to count.
Up would be best, then fly east.