Using elevator trim and power to control decent and flare is a valid emergency manoeuvre if you have a stuck elevator.

I agree. That's bringing another variable into the mix, providing yet, one more thing to go wrong, if something goes wrong. Right?

Very bad habit to get… never do this in a real plane or you will increase your chance of a departure stall if you have to abort landing. Always hand flare.

Terrible idea. Just take the firm landing. If you can use the plane again it's a good landing!