you dont really need any lawyer for this,,you'll end up paying a lotttt of money for something you can do yourself,,,
as for your bf,,i recommend him not to tell anyone he is getting married with a Canadian,,,this happens all the time and when they find out he will be already out of Cuba,,(note a year ago cubans needed a permission to leave cuba,,thats when they went to get their passports they had to say what for and immigration informed the hotel that he was getting married) but,,the permission to leave was abolished in 2013 so,no need to say anything now..
source: myself,i am cuban,,i worked at a hotel,i am now in canada.