>Am I right with the commas in these exemples ?
You could say that, but there is a twist.
Take a look at what may have happened to Mark the intelligent.
As long as the main clause is in the affirmative, both versions are unambiguous.
(1)Mark managed to survive because he is very intelligent.
(2)Mark managed to survive, because he is very intelligent.
(1) emphasizes the reason for Mark's survival
while
(2) emphasizes Mark's accomplishment; the reason for his survival is secondary or, well, subordinate, as it were.
(1) and (2) don't mean the same, but both are OK.
But when the main clause statement is in the negative, the comma is critical:
Mark didn't survive (no comma) because he is intelligent; he survived (no comma) because he was lucky.
Mark didn't survive, because he is intelligent; he died, because the policemen first had them take an intelligence test and then decided to killed the most intelligent one of the bunch.