I know you can do as many maneuvers as you feel like using fatigue points, but what about action cards?

Do those follow the same rule? Could I effectively launch as many attacks as I want as long as I pay fatigue cost? I can't find this in the rules.

Only one action is allowed per turn.

The only exception that I am aware of is the use of active defense cards where you use the action on another player's turn.

Lionyx said:

... and the rules for Quick Casting.

and some actions get to repeat of you can pass the challenge difficulty...