Oh...one member had replied but deleted his post..
Ok so rudder trim is never applied during manual flight by the computers, unless we turn the rudder trim selector manually. This pretty much answers my first question.
Furthermore, I received a pm telling me that I was getting confused between Turn Coordination and Rudder Trim..
So if rudder trim is never used during long turns (AP engaged scenario), when would AP decide to apply rudder trim (of course, except engine failure..)? Is there any flight phase during normal operations where AP asks for Rudder Trim? Maybe cruise? Or on short final in windy conditions?
Thanks.