To the best of my knowledge Bill Bonanno's associate Carl Simari was never shot or killed. I believe he just faded off the scene.

Gaspare DiGregorio's stepping down from the boss position had more to do with his extremely poor health (he had a series of serious heart attacks both before, and after, his ascension to leader) as well as his lack of zeal regarding the gang-war and its fallout. I'm sure his health played a major part in this lack of focus and abilities, and reduced desire to lead. He essentially relinquished his post voluntarily. His choice. He wasn't forced to step down. Quite frankly, Paul Sciacca wasn't a forceful leader either. He was a 'weak sister" so to speak. Only with the election of Natale Evola to become "representante" did all factions finally align with the hierarchy. "Joe Diamond" was a very well respected man. Unfortunately he passed away several years later (73' I believe) which led to another round of splintering in this family.

Note: Gaspare passed away only a year or two later after stepping down if my memory serves me..