Paul,
I wanted to give some examples of fundamental physics, which cannot be truly understood in a non-mathematical fashion. You may read very good popular books and get the impression that you understood them, but you really understand them when you understand them geometrically. I started to compile a list, and then I realized that the list will be difficult to read, and you will pick up some details and contradict them, without trying what I say. Moreover, as you said, my statement was about fundamental physics in general. Therefore, I think that it would be better that you pick some phenomenon of fundamental physics, which is today understood, of course, and which you think that you can fully understand without mathematics. According to my statement, I should be able to show you that you can understand it better if you understand it mathematically. But the only way I can show this to you is by telling you what to study to obtain this understanding (assuming that I understand this phenomenon myself and I can guide you). Otherwise, our long discussion reduces to me telling you how good is a special recipe of ice cream, and you providing philosophical arguments supporting the idea that you will not miss anything by not tasting it.
You say "Reality is not coordinate-free, however." I disagree. A coordinate-free object doesn't remain the same by changing the coordinate, but rather it's "shape" remains the same. If you want to understand what mathematical physicists know about coordinates, and by coordinate-free objects, you can read something on differentiable manifolds, special and general relativity, and gauge theory.
About motion. Motion is change in time. Change of what? Of a state, or of a configuration. All possible states, or all possible configurations of a system, in a particular theory, form an abstract space. Motion is change of the state in time. Therefore, motion is a curve in the space of all configurations or states, parameterized by time. Any physical phenomenon which is currently understood has such a description. Can you think at a different kind of physical motion, which is not completely describable like this? For the motion, I would recommend something on Lagrangian and Hamiltonian mechanics, Schrodinger equation, and perhaps dynamical systems in general.
On your observation about time as a fourth dimension, I would say that explaining time as a moving 3D-space in the 4D-space is wrong, and this is not the way time is understood as a fourth dimension (or at least those who understand it like this are wrong). The first idea is that all the equations describing physical phenomena happening in space have as solutions fields, which can be defined equivalently as time-evolving space fields, or as space-time fields. Therefore, all the information is contained in the space-time fields. The second, and most important reason for viewing time as a fourth dimension, is due to Lorentz transformations, which rotate space components into time components and time components into space components. These two clues suggest that, at least as a representation, time as a fourth dimension satisfies all the physical needs. Mathematics explains relations. Some may disagree, but can they show a physical phenomenon which is not describable with time as a fourth dimension?
You say:
"Tell me, how would you describe particle, nuclear, and atomic physics and chemistry to a native in a small village in Africa who only understands a language that does not even have words adequate to describe the basic concepts? It is an interesting problem, but not insurmountable if the native really wants to know."
It depends on how much they want to know. If they want to have an idea, popular science books can be enough. If they really want to know, I am sorry, but they will need to learn a lot of mathematics and physics. And the mathematics is not just for being fancy, it is necessary. I respect your thoughts, this is why I did not come to you and tell you that you need to learn math. It was you who came to me and told me not to use math. I cannot show you the importance of math in physics, if you don't jump and swim. It is your choice, I don't want to insist at all. The discussion was continued because you asked me to resolve some of your doubts. But if the doubts keep coming, there is only one solution: go and see. Take a particular phenomenon and explore it. But it's up to you.
You cannot describe with words a symphony to someone, the only way is for him to listen that symphony (or you can show him the sheet, if he can read it).
Cristi