Flap parts in B9 are enabled by holding the (default) brake key. (B), or clicking the brake button on the screen next to the altimeter, below the lights button.
I've never messed with FAR, I'll have to take a look into it sometime.
To make a flap. (stock)
1.Use any of the ailerons
2. disable the roll/yaw/pitch
3. Set them to deploy in an action group, or with the *brakes*
From my continuous testing with my replicas, sometimes flaps can do unwanted things, such as making your plane pitch weirdly.
Hope I helped!