info on linking textures

I’ve assigned a material and a texture to an object, and then wanted to make the texture show up in Object mode, so I linked the texture by selecting it in the UV editor.
Unfortunately when I export the object as an obj and open it up in another program, those linked textures are showing up as additional materials. The only way to get rid of them is to go back into blender and unlink them, then reexport the OBJ.
I have 160 objects in my scene, and was wondering if there is an easier way to unlink those textures, than to select each object, go into edit mode, select all and unlink 160x.

My second question is what exactly does linking a texture do? What’s different between that and assigning a texture in Object mode. I always just assumed it allowed you to see the texture in object mode, but if it’s exported along with other materials, then there must be more to it than that.

I have a similar problem with about 100 objects in blender and a terrible workaround.

I have a object in one file with a material and a texture.
I link this to a second file and the texture appears correctly and renders correctly.
If I change the texture in the original file and look in the second file, the material and texture appear greyed out in the properties menu, but does not appear in the 3d view or render.

If I relink the object in the second file(which is a pain because I change the textures a lot), it does display correctly in the 3d view and the render.

Any help would probably help a lot of people.