I see people on youtube when they're making custom zombie maps, use tons of cool models etc. for debris or other. However I don't have any of it. Is it seperate from the WaW Mod Tools?

You can port custom models/textures from other games like BO1/2 for instance. You need Toms Lime to do that and there are few tutorials out there

Solved, It was me who didn't know where to go (which folders etc.).

Usually you will be in prefab, however when you want to find the Misc > Models and place stuff like, wheels, lights, barrels, flags etc. etc. You need to go back into your Call of Duty World At War folder, then Raw, then xmodel. There you go in case you had the same problem i had