Just as Roth was Lansky, Ola was Jimmy Blue Eyes (although in real life, Jimmy wasn't the lackey that Ola was portrayed). But, just as Lansky counseled most of the families, so Roth, as described by Ola, "always made money for his partners" [emphasis added]. So, while Vito brought him up in the Mob life, Roth was clearly an independent operator, not a Corleone monopoly.

Altobello may or may not have been in the Corleone family, but if he wasn't, he was damned close to them. I don't think Vito would have selected him to be Connie's godfather otherwise.

I have always believed that Vito was a composite of several Dons, including Profaci (olive oil king), and Bonanno (brings his son into the business). But the one he most closely resembles is Frank Costello, "Prime Minister of the Underworld," who eschewed drugs, dominated gambling and unions, and was the most politically powerful and sophisticated of the Dons.