1) I’m only using the EVU function as that is easiest
2) I run it based on hours and terminate an ongoing run. It could make sense to let it complete a run before terminating.
The amount of hours differs depending on your house and hotwater consumption. If you set it to low you will not be able to maintain the indoor temperature or might get to much variation in room-temperature. Give it to many and you would save less.
The whole idea is to push consumption to low-cost hours and sacriface by a larger variation in temperature. Actual variation depends on your house’s ability to store energy, kind of like a capacitor smoothing out a voltage variation.
3) I would try to keep all floors active as much as possible while the heatpump is running.