User blog comment:Supahbadmarine/Official Canon Policy/@comment-5571814-20130219062628

1. I would say keep them ambiguous as to whether or not they are descended from either of them, though the Space Wolves seem to be too unstable to foster successors.

2. This one is tougher, but it could be possible. But then, I'm not up on the lore.

3. I would put the limit on 100, and maybe a few colonies. Unless it's out in the Eastern Fringe, anything larger would not be able to exist very long.

4. The Necrons are obviously the top tier; nothing can surpass or equal them, as with the Eldar. Being on par with the Tau have might be more reasonable, but this would be tricky to balance. Surpassing the Imperium is commonplace, though not to the point of rendering it impotent against the faction. It may be crude, but it is still very powerful. If they are DAoT advanced or beyond, they need to make it reasonable.