Maranzalla, as he's so called, is mentioned twice in the Godfather novel. I always thought he was a fictional counterpart to Maranzano....But later on Maranzano is mentioned, and Maranzalla is completely forgotten about, after a brief reference. Does the latter play any part in the story?

Also, in the book, Puzo has twisted history slightly by stating that Salvatore Maranzano was killed by the Corleones, in the exact same method that history dictates Joe Masseria was killed.
I've read about this before, but can someone remind me how Maranzano was really killed?

Six months after Masseria was killed Maranzano was planning on killing some of the newly appointed heads of the newly formed 5 Families. Lucky Luciano, one of the intended victims, got wind of Maranzano's plans and countered with his own hit-team (made up of 4 Jewish gangsters who were unknown to Maranzano). Thomas Lucchese, whom Maranzano considered to be on HIS side, but was really present there to set up Maranzano, fingered the Boss for the 4 gunmen who were posing as cops. They shot and stabbed Maranzano and as they were all running down the stairs to exit the building they passed Vincent "Mad Dog" Coll who was going up to kill Luciano and Vito Genovese.

This happened September 10, 1931, on what is popularly called "The Night of the Sicilian Vespers" (although there is no proof of any large scale murders that night).

To add to SC's excellent post:
Puzo borrowed lots of material from real life. In effect, the guy he portrayed as "Maranzalla" was really Joe (the Boss) Masseria, who was killed by Salvatore Maranzano in the famous Castellemmarese War of 1930-31. And Puzo put Vito Corleone in the role of the real-life Maranzano in that episode, right down to killing "Maranzalla" in a restaurant.

Read again Turnbull, in the Novel the guy who is shot in the restaurant by Tessio's men is called "Maranzano", so Puzo switched names. Maranzalla isn't mentioned in the book after the part in which Vito kills Fanucci, who was working for this guy "Maranzalla".

Woa! was Turnbull just proved wrong???? I never thought that I would see the day...