Jigsaw is descended from Ladd RussoJigsaw's real name is Billy RUSSO, is a member of the mafia, and was very handsome before Frank got his hands on him. Ladd from Baccano! is also a handsome mafioso. Obviously, Jigsaw is Ladd's son or grandson.
The Punisher doesn't kill Kingpin, because of lingering mental controls.When the Kingpin had third rate psychic The Persuader brainwash Frank Castle, he had the guy place into Frank's mind subtle commands to avoid going after the Kingpin. While Frank broke with the overt control, he never did overcome the subtle commands. And so, he justifies reasons not to go after Kingpin.
The Russian (movie version) was the result of a Soviet effort to duplicate the Super Soldier SerumFor which he was a partial success: it gave him extraordinary strength, reflexes, and durability... but also gave him significant psychological problems.