There are four major groups of Kamis. Two of them staff the bureaucracies of Heaven and Hell respectively, while the third group tend to be the spirits of places and things. The fourth group blurs into the third--the Archetypes, who tend to represent more abstract concepts, like Justice, Hate, Japan, Elvis, and Smurfiness.
All Kamis share certain properties. Their natural form is a spirit body which is imperceptible by humans and not subject to the normal laws of nature. On the other hand, this body also usually can't do much to the physical world except watch it, so they typically take on manifestation bodies. These bodies are killable, but since it is not their true self, it is very difficult to slay a kami permanently unless you catch it on another plane of reality in its spirit body. The one exception to this is place and thing kamis, who can be destroyed by destroying the thing or place they incarnate. In addition, changes to that place or thing will effect them as well. Archetypes are also somewhat vulnerable to this, but some are more vulnerable than others. Good luck getting rid of Death, Justice, or Taxes, but you might be able to elimate something like 'Japan' or 'The Twelfth Amendment'.
Kamis are effectively immortal and unaging. Some Kamis can reproduce and have children, while others cannot. Presumably there is some reason for this, but either the Kamis themselves don't know, or they just don't want to tell anyone. Some Kamis can mate with mortals as well, while others cannot. Again, there seems to be no coherent pattern on this, except for a handful of Kamis where it is obvious why they can do this (Such as the Archetype of Mad Passionate Sex)
The power level of Kami manifestation bodies varies greatly, from Kamis who could be beaten up by five year olds with a pointed stick to ones who could snuff worlds with a sneeze. The same Kami may vary the level of their body at different times, ranging from a desire to be inconspicuous to marching orders from the Power they serve.
The Kamis of Heaven
The Kamis of Heaven are organized
into multiple parallel bureaucracies whose precise relationship is unclear,
even to them at times. Ultimately, all the Kamis answer to the Lord
of Heaven, the Celestial Emperor, Kamisama. It is unclear whether
he created the first Kamis from nothing, sired them, or what. Some
can definitely claim to be his children, but their power level varies tremendously.