1) Colombo was killed by calculations by Anthony Abbatemarco, Jerome Johnson lived above a place that Abbatemarco frequented, and yes it was a Gambino place.
2 Jerome Johnson was killed by Phil "Chubby" Rossillo in front of the cops and nothing happened to Rossillo that he became a legend for it.
3) Joe "Crazy Joe" Gallo was killed by Carmine DiBiase, and the LoCicero brothers, along with some others on orders form Joe Yacovelli. Everyone is dead now except for Frank LoCicero who might still be kicking but he is in his 90s.