Probably there is a combination of factors explaining why Leonard fought "Duran's fight". One obvious reason is that Montreal Duran commanded the fight and overwhelmed Sugar. But I still think that somehow Leonard also decided to go punch to punch with Duran because he had something to prove that night. There is a well known story about Duran stalking and harassing Sugar's wife days before the fight. Quite disgusting stuff. Thus it seems Duran got under Sugar's skin after all and that would be one of several factors explaining what happened during the fight.
Oh, hell yes. THAT Duran landed punches from every possible angle. The stamina, too, to keep 'em coming.
Nope, Benitez would outbox and frustrate Duran 100/100 times. Benitez was great fighter, he was Duran's cryptonite and Duran was tailor made for him.