A lich can be good or evil, depending which side of the fence its creator lies on. These are a created race and are, as such, restricted. Please see staff before having a necromancer create one.
Liches, in many cases, are a race that never should have been. They were not created by the gods, but by man and are often seen as blights by most religions.
Unlike most zombies, Liches retain their sense of self, memories, and to a certain extent, even their soul. The necromancer who first created them, whose name has been lost to history, bound the skeletal corpse of a living man to the world by sealing its soul in a Phylactery. Without this, there is no Lich.
They are made to serve their masters. To be more intelligent than cannon-fodder and to be more powerful than it as well. Liches in history have risen to surpass their creators, though this is often a rare occurrence for details that will not be outlined here.
A lich can survive in most habitats, including underwater as they have no need to breath. Any places hot enough (such as volcanoes) that would cause their bodies to combust they stray away from (like any sane individual should.)
However old you were when you died + how long you've been a lich. Liches, in theory, are immortal lifespan wise so long as their Phylactery stays intact.
However tall your skeleton was.
A lot lighter than you used to be. This varies so its hard to say.
Liches have no need to consume any food.
Liches are dead, thus they cannot breed. One Lich typically cannot create another Lich either. Some exceptions may apply.