This may be a distribution related issue - and "does not involve KDE" -
although since Firefox is bundled is Fedora gnome and Konqueror is relegated to KDE . . .
I'll go on the (perhaps mistaken) premise that this should at least be good enough for being in consideration on a KDE forum.

Firefox - after I loaded it into my F12 KDE Live - does prompt to be the default browser - but how to get it to either . . .
(a) really default as the web browser
or (b) have it at least listed as an icon along with the web browser choice for Konqueror.

Thank you very much.

The default web browser can be set in System Settings > Default Applications.