Is spin just a substitute for an unknowable quality in elementary particles? I just assume color is. How is spin possible in something fundamental. Are there actual surface features on or around a particle that literally rotate around it?

It should not be thought of in terms of something rotating, like angular momentum. It is an intrinsic property of fundamental particles as well as composites. It is really a consequence of Lorentz symmetry and is very natural in special relativity. In non-relativistic quantum theory it is simply "bolted-on" to the theory to reflect empirical evidence.

 

To understand spin properly one needs to think about representations of the Lorentz group. Do you know a little group theory?

Not yet, but give me a week. Thanks for the response. That's just the kind of information I was looking for.