Newark did have it own family. It was disbanded by the commission through Joe Profaci, and the family was split between the 5 NYC families, Philadelphia family, and the Decavalcante family. It was powerful, but there were frictions from the old Maranzano and Masseria fued, even though Monaco was killed at the same time as Maranzano to avoid anymore fighting, there were still hostilities within the crews.

Your question about Atlantic City. It was opened as long as one followed by Nucky Johnson's rules. Back then there were two ways to get to the city, by train and by boat. Some mobsters(Philadelphia, Genovese, Gambino, and Newark) showed up there. But most were Jewish mobsters, and Lansky had a person down there that was controlling a lot of the city's gambling through a relative of Frank Erickson, while the strongest Jewish power in Atlantic City was held by Max Hoff of Philadelphia and Joseph Reinfeld of Newark. It was really all about geography, plus many of the Italian mobsters back then were set in the old world mind set, while there were some that were smart, like Luciano and Lucchese. You see a lot more organized crime committed in Northern Jersey than in Southern Jersey, because there were a lot more road up there that were heavily travelled.