Toon shading with overlaying textures.

Hey, I recently thought about messing around with a couple short cartoon animations. I googled a bunch of different ways of toon shading in blender but ran into problems. I cant seem to get a texture to over lay on the toon material.
For example if I wanted to put letters on a t shirt, or extra details into a brick wall. I will attach a few pictures below and hopefully you can help me answer some of these questions.

  1. Is there a more efficient way of toon shading.
  2. Is this possible in the principled shader.
  3. How can I get another texture to overlay my toon material !!!

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