Travel time into downtown Havana is about 30 minutes; to the Varadero hotels - 2 hrs.
Minibus transfers can be arranged with tour operators, and a single person can buy a seat if space is available.
Currently there is no public transport (VIAZUL) from the Airport. While public VIAZUL buses are not available at the Airport, other local buses into the City are available at Terminal 1 only - reached from other terminals by airport bus or taxi; however, payment is required by non-convertible cuban pesos!
The VIAZUL bus station in Havana is in the Vedado district - l5 km from the Airport.