How would I go about extracting models from a pc game?

[Garamonde]

There should be separate files for the textures yes (are there? And are they in .PNG? If they are in .TGA then they will need to be converted).
Those have to be included in the same folder as the model.
While the .DAE usually stores texture data on the model, you always want to have the spare textures there in case anything goes wrong or someone needs to texture the .OBJ.