Texture Graphics for Units Help

I have a texture of the water element, and I put the path on the exact water elelment. I was wondering is there a way to make it so that you can create more textures for the same unit, like he'll be a fire and wind element.

Yes, but it involves copying the Water Elemental model, specifying a new skins path in it, and importing both the new model and the new skin into your map.

Although if you're okay using the somewhat similar Sea Elemental (the Naga summon) for the base model, you could have two imported skins before having to add any models.