Thanks for your overview of the "anti-oath" movement of Jesus' day. It's helpful. One of the guidelines I offer students of the New Testament goes like this: "Always remember, the words had to mean something to those who first heard them. Seek for that meaning. Find it, if possible. Build your interpretion and application of texts on such a base." Some listen, some don't!
Turning to some of the matters you raise, like you I sometimes wish we could find a better term than "kingdom" for use in contemporary America. I'm not sure "the vision of God" and "vision people" suffice. In Christian theology, for the most part, "kingdom people" are those who live (or try to live)in constant awareness of the rule of God. There is a living God at work, both generally in all creation and specifically with individuals. I suspect our different views on the nature of God are at work here.
Personally, I prefer to use "the way of Jesus." The phrase (for me) implies choosing a life direction centered in and guided by Jesus. All elements of life come into play: the mind, the emotions, self-care, caring for others, worship, daily "bread," work, play, rest, and the like. As you know well, "people of the way" probably was the earliest self-description Christians employed. I think they were onto to something important.
With regard to swearing an oath of fidelity to Caeser, I think you've identified an often overlooked yet highly probable possiblity. By the last decade of the first century, such an oath figured into persecution of Christians in Asia Minor. Insofar as I know, we do not have recorded incidents prior to that time. I am intrigued by your reference to "a general Pharisaic refusal to swear an oath of loyalty to Caesar" and would like to know more about the probable dating.
The larger issue, of course, is idolatry. When we place our ultimate trust in a system, a person, an ideology or any thing other than God, we divert from "the way." We may run off the road and into a ditch or wind up traveling another road, if we stay fixated on the diversion. My hunch is that all economic systems (to stay with the matter you suggest)hold the potential to divert us. The same is true of what we might call professional recreation, the entertainment industry, or even our personal avocations.
Living on "the way" requires one's attention, to put it gently.