I am a warlock and I don't know what kills me and what don't kills me. And what about the other species? What kills them?

You CAN be 100% sure that Death kills everything. And you have to be a bit more specific about what you mean.

If someone hit's me with a athame. Am I dead?

Well... I guess that depends on a lot of factors. Use common sense. Warlocks and demons are stronger than regular humans, so you can be sure one stab won't kill you. But still, common sense. You don't die from a stab in the shoulder.

And what if it's a very filthy coal pocker? Does wound enfection works on demon?

And another thing... can comeone make a potion to vanquish a demon =>insert a name here<= ? I mean a specific potion to vamquish this particular demon...

Oh dear.

Lots of things kill. Usually of the physical variety. If you get stabbed in an area that's got losta lovely organs, say your chest, stomach, then it's much more serious than as a shoulder as Blaze suggested. Also, as Blaze suggested, use common sense!

Unless you really want to make things difficult for yourself, don't think about infection. Sheesh. That's just getting far too complicated.

Making specific potions is an idea, but, as with all potions, it is not certain to work. Remember: if you throw a potion or cast a spell, you must wait for an independant post from The Powers for the result.