When I hover over an URL in konsole (or some program like vim running in a konsole window) the URL is highlighted (underlined) but clicking on it has no effect.
Is there some way of enabling such a click to bring up the URL in my browser (Firefox)?
You can right click on that URL, and select "copy link address"
There was a thread about making Firefox the default web browser through the KDE menu...if you can make that work, then you could right click on the URL and then click "Open Link".