How often can you use their abilities per turn, I'm specifically asking about Sato but Ackbar and Mon Monthas abilities appear to read the same.

Every time it is applicable. Mothma could apply to a single CR90 four times in a turn if it somehow got shot 4 times and hadn't died.

Ackbar works on every shot fired out a ships side arc at another ship that turn.

Cracken obstructs every very shot fired at his ships regardless of #

Vader once per attack. Screed once per ship activation. Sato once per attack. Ackbar for every broadside provided no non broadside attacks are made.

Everything else is a bit simpler I think.

Cheers