I don't think there's a single answer for those questions - it's all situational. Seems to me that a boat at a dock or in a marina is likely subject to some kind of surveillance camera and would require keys or some sort or a highly technical knowledge of how to start a boat without keys.
A smaller boat with a manual start would likely be trailered somewhere and not simply sitting in the water ready to steal. So it would need to be put in, without being observed in the act of theft.
And then what? Drive a stolen, unknown boat to Cuba? I'm sure it's do-able weather permitting but that's not like hopping in a car and driving and I don't know of any evidence of him having significant maritime experience. Then, of course, what does he do in Cuba? I don't know but he would seem pretty conspicuous arriving in Cuba.