Hello @katiekm and welcome to Debbie's forum! So I believe you will have 14 days to travel From Varadero to Trinidad to Camaguey - Santiago de Cuba and Baracoa and than back to Havana.
Will you rent a car, or you will have your private driver or you will use Viazul?
If you are on the budget you should travel with Viazul bus service that is air conditioned and on time.
Please visit http://www.viazul.com and I would suggest that you buy tickets in advance online as that way you will be sure that you have tickets and do not get disappointed when you are in Cuba that tickets are sold out. This way you can plan your trip accordingly.
As well you should buy air ticket in advance to return from Baracoa to Havana http://www.cubaero.com/index.php
Keep in mind that there are only 2 flights per week on Thursday and Sunday from Baracoa to Havana and you can buy tickets online in advance as well. Another option is Cubana airlines http://www.cubana.cu/ and I see now they have flight December 27th from Baracoa to Havana for 183 EUR one way. Keep in mind that you will need to pay taxi or driver to take you from airport in Havana to place where you plan to stay in Havana.
14 days in enough in my opinion to visit all 4 cities Trinidad, Camaguey, Santiago de Cuba and Baracoa.
Personally I would spend 3 days in Trinidad, 3 days in Camaguey, 5 days in Santiago de Cuba and 3 days in Baracoa.
Keep in mid that Santiago De Cuba is the second biggest city in Cuba and lots of to explore and see. Let me know if you have any other questions regarding Baracoa or your trip to Cuba
Is it your first time visiting Cuba?