I've looked thru info on hand as well as some new info - getting closer to understanding more.
For the ideal capacitor the capacitor looks like an open circuit at DC and gets closer to behaving like a short circuit as frequency increases - so current a capacitor could handle increases with frequency.
It appears that ESR (Equivalent Series Resistance) and DF (Dissapation Factor, a cousin of ESR) are used to represent an undesireable characteristic of capacitors. ESR or DF result in power loss (as heat). ESR, among other characteristics, is not flat or constant but changes with temperature and frequency (at least).
In many applications the losses aren't that important. The voltages applied are combinations of DC and AC and the proper capacitor is often determined by the reactance required and the max voltages that will be seen as well as frequency (with due regard for stability, temperature curves, etc).
In some applications the capacitor sees AC at high frequency and the losses can overheat the capacitor long before the voltage limits are exceeded. There are some good rules of thumb related to the surface area of a common capacitor (disc ceramic, silver mica) that suggest limits of power loss. We put ESR and DF to work in determining the heating or power loss for a given application.
So, I am getting closer to understanding how to establish reasonable limits. I am going to crank thru some of the math eventually and will see what I see. Will share with anyone who contacts me -
WA2EKL@arrl.net It remains to be seen if my work will be worth "publishing" in some small way. At best it will be a simplified version of what's already been done by others.
Please, if this has already been done and published, point me to the article, document, whatever.