Aside from the knockdown and the vigorish, are there any other types of loansharking out there employed by the Mafia?

Loansharks will lend money to other loansharks at 1% interest per week and those other loansharks will push it out on the street at 2%-3%.

Correct.

Part of the Westies-Gambino alliance perks for the Westies was that the Gambinos would give the Westies $ to run a shy at 1% vig, which is the % rate the family would give their own soldiers.