To be pregnant, an equilibrium in ph and chemical contents of the uterus and the outside environment has to be maintained, to prevent any reactions of the chemical sustances taken in by the person pregnant and the baby *has something to do with concentration gradient, hence yes, pregnancy can count as homeostasis
Fire can be accidental or intentional, and it can cause erosion.
They're considered to be human like hands. They have a thumb like humans which allows them to grip onto trees and maneuver better. It also helps them with their grip onto branches and trees because they rarely come down from up there, so they need to be able to grip tightly even a sleep. I would say it's natural selection due to evolution.