I don't remember what town I was in but I fell off of scaffolding on the 2nd floor and was killed instantly. This is more likely to kill you than 1 meter, however, I wouldn't expect anything more than broken legs at the most from that height.

This happens to me frequently. I've locked myself inside several times and had zombies attack me through walls and from different floors. I have also had them glitch through the walls and come in and attack me as well.