1. Don’t have that option in any of our aircraft, so can’t comment on the FMS. We can do packs on or packs off, APU not involved. In the FCOM it says to use both packs on the ground if available, as the fuel burn is the same as using one. “AUTO” is a good setting for many of the controls.
2. The answer to this one that I got from a Boeing engineer was that the system automatically checks that the control surfaces are moving correctly and relative to inputs on the controls. If there is a problem, you will get a Caution/Status. Much in the same way that if any other monitored aircraft parameter goes out of normal operating range, you will get some kind of notification.