Dear Javier,
All of your assumptions are correct except (4) and (5). In FAST v7, positive yaw angle and positive wind direction are defined about the positive zn (d2) axis (counterclockwise when viewed from above). The complication here is that FAST’s module AeroDyn defines the wind direction differently–in AeroDyn, a positive wind direction is defined about the negative zn (d2) axis (clockwise when viewed from above). So, if you input a positive wind direction in AeroDyn’s wind file it will show up as a negative direction output from FAST. See the following forum topic for more information: Is positive Yaw error clockwise?.
I’m not able to see any of your figures, so, I can’t comment on any specifics. I will just say, though, that free-yaw wind turbines with upwind rotors can remain stably upwind in some wind conditions; however, there are certainly wind conditions where the upwind rotor will yaw downwind. Likewise, it is known that free-yaw downwind rotors can become stuck upwind, potentially to its peril.
Best regards,