I think this is partly a question of vocabulary, and partly a reflection of the fact that the longitudinal Coulomb oscillations you describe fall off so rapidly with distance. (Basically $1/r^2$ instead of $1/r$.) Therefore they are usually called "near field effects" and are totally dominated by the transverse "waves" after a distance of only a very few wavelengths. Nevertheless, they do exist, even in a vacuum, and they do extend to infinity, just very, very weakly.
In short, if there is nothing to interact with the wave, it can't lose energy. EM and gravity waves do not experience friction with vacuum, so they just keep going.
Of course, as they spread out, their energy becomes spread out as well. The power per unit area, or flux, is (somewhat trivially) inversely proportional to the area of the wavefront, so as long as this area is increasing, the wave's local "strength" decreases.
Edit: Taking the philosophical tack (which is certainly fair - physics was indistinguishable from philosophy for most of its history), I suggest analyzing things in a Leibnizian/Machian way. For both of them and their followers, all we have is measurements of how things move relative to one another, and any background "absolute space" (à la Newton) or "field" (à la Faraday) is just a mathematical invention that proves convenient for describing these relative motions.
When you turn on a current in a wire, the moving charges can make other charges at a distance move in response. The way in which these other charges respond is nicely described by first defining a magnetic field from the current, and then applying the appropriate force law for charges in a magnetic field. There is no distance beyond which the other charges are not influenced at all by the current, so the "magnetic field" (aka "influence of the current") extends to infinity. Furthermore, those distant charges won't "know" about the current until sufficient time has passed for the information about it to reach them, and hence the leading "edge" of the magnetic field moves outward at the speed of light.
Best Answer
No, the magetic field from the magnet will not affect the light. This is called the principle of superposition, and it says the fields themselves don't interact with each other (at least classically. In the quantum theory, light can scatter itself.)
However, the light from the flashlight may interact with magnetic (or electric) material. This is where you can get the behanior BMS speaks of in his answer.