Zombies Abilities

A usual question that comes up when you're talking about Zombies is their abilities/ powers.
I've researched this question a little bit and have my own ideas of what they're capable of.
Zombies never sleep, and they are incapable of fatigue. Fatigue in the muscles is caused by a lactic acid build up. Zombies are incapable of producing this acid. Since they are incapable of producing lactic acid in the muscle tissue they feel no symptoms of fatigue. They also feel no pain, because the nervous system shuts down after "death", making them unable to feel anything. Zombies also require no air to "live", because they use such a small portion of their brain that if their just in an environment where oxygen is present they can "live". Knowing this you could say that zombies could live underwater, but that thought is misleading in my opinion, you would think of a zombie walking on the bottom of a lake then coming up on the other side. This wouldn't happen, because the human body during decomposition creates gas through out the body and would make a zombie float rendering it quite useless and at the will to the current. They are immune to drugs, poisons, gases, suffocation, and drowning. They fear nothing, zombies don't have the cognitive capacity to know how or what to fear. While not invulnerable to physical injury, zombies can suffer immense amounts of damage to their bodies without "dieing", except damage to the brain. Zombies can eat and eat and have no sense of being full, so that means their is no prime hunting period for zombies they're on the hunt for you 24/7.