They have named this automation confusion AirRabbit.
Just went through this the other day. 10 miles back, airport in sight, autopilot off, "both f/ds off". Of course we left the ILS raw data on, and I turned the FPV on as well. Then the comments start:
"I'm going to leave my flight director on" (Scared to fly without it. No understanding of autothrust behavior with pnf FD left on).
"Why are we in track fpa? That's only for non precision approaches." (No understanding of track/fpa mode. No understanding of what the FPV really is for).
These guys are fine as long as the autopilot is flying the ILS or fully managed NPA, and they have the required incantations in both SOPs memorized, but they don't understand what the airplane is doing. Take them outside of those two situations and they are totally lost. As for your point number 4, the mental gymnastics these guys are capable of to justify blindly following the plane into the ground rivals the intelligent design crowd. During the same day as the above, after having 3-4 red lights on the PAPI for the last 500' while following the brick all the way to touchdown on an NPA (in temperatures lower than -20°C):
"I don't know why the PAPIs were red the whole way, but I don't know what eye to wheel height they are good for anyway".
To provide more information on your question Tony, the F/D will provide good guidance all the way through touchdown and rollout on an ILS, but will not do so on an NPA. So you CAN leave the F/D on during an ILS, but you are not REQUIRED to. Feel free to turn them off. On an NPA though, the F/D will not provide good guidance below the MDA and therefore MUST be turned off.
So in both cases, the FDs can be turned off. Once they are off, it would make sense to turn the TRK/FPA mode on, as this is the only way to get your FPV on, which is a handy thing to have.