In the early 1930s, through mob contact Dominick "The Gap" Petrilli, Valachi was introduced to the Cosa Nostra or Mafia, and soon became a soldier in the Reina Family (now known as the Lucchese Family) during the height of the Castellammarese War. Valachi fought on the side of Salvatore Maranzano, which eventually defeated the faction headed by rival Joe Masseria. After Masseria's murder, Valachi became a bodyguard for Maranzano. However, this position was short-lived, as Maranzano himself was murdered in 1931. Valachi then became a soldier in the family headed by Lucky Luciano (eventually known as the Genovese Family), in the crew headed by Anthony "Tony Bender" Strollo. Valachi remained in this position until the time he became an informer.

He was the son-in-law of Gaetano Reina, having married Reina's oldest daughter Mildred in July 1932, over the objections of her mother, brother, and uncles.

you're right redbullets the other the other families were not as secretive as the Genovese family was, also Valachi has begun with what would become the Lucchese family, also was not a soldier of such a low level as you may believe, since it was a friend of Vito Genovese that also made by best man.
Reading his earliest witnesses see who knew the five families but didn't give information on families outside of NY. For example, he didn't know that the family of Buffalo was called "The Arm" or that of Providence "The Office".

About the Sicilians they consider foreign anyone who is not Sicilian.
For the use of the word "Don", is used as a sign of respect even from me in Campania, but is only used by the old men. So once Eppolito visited Castellano in the 1980 spoke to him as Don Castellano, and Big Paul said "don castellano? we aren't in the Godfather?"

For Greg Scarpa is different when he accepted to cooperate with the FBI in 1962 to avoid prison was a soldier like many others, he eventually climbed the ranks to become in the third colombo war, the street man of Persico exploiting DeVecchio for information to kill 19 the men of Orena.