How many gods are there in WH40k? And how many of them "exist"? Firstly, lets look at the gods:

Astartes/ IG/ Loyalists: The Emperor, The Machine God
Chaos: Khorne, Tzench, Slaanesh and Nurgle
Eldar: Khane' (possibly the same as Khorne?)
Dark Eldar: ???
Tau: Science and Technology!
Orks: Gork and Mork
Tyranids: ???
Necrons: The C'Tan

And by "exist" I mean, how many gods do we "see in action" so to speak. We obviously see the Chaos gods since there are CSM with all the marks and gifts of their gods. The C'Tan exist since the Nightbringer and Deciever exist. But what about gods like Gork and Mork? We don't see anything of them anywhere...

Finally, if all these gods exist, then why don't they fight their own battles instead of using the people, aliens and beings in the 41st M to fight for them?