Yes, indeed: thank you, rudge - that method does work, although I did encounter some initial difficulty with it. Apparently, when the taskbar panel height is lowered to the amount that I prefer, it becomes impossible to grab the icons anyway - so; the taskbar must first be raised, then the icons arranged, then the taskbar must be again lowered. At any rate, it's been dealt with now, so let us proceed onwards.
First though, a brief glimpse back at the typeface situation: I've still not found a suitable TrueType typeface; however, I think it likely that by now I should be able to deal with that situation on my own behalf - it's simply a matter of finding a suitable typeface, adding it into the font manager, and then specifying same in the theme - correct?
So. The real remaining issue now then is precisely that: the theming. I'm still hoping to get it surrounded - but I need first some key piece of elucidation; an accurate map of what is utilised in common. There must be some theme elements that are referenced as such, for I've noticed on two more fresh installs already that the Plix theme does not on its own make the systemtray background transparent. It is only on this 'testbed' machine with the initial KDE4 install that the systemtray background is actually transparent, and the only way that could be so must surely be attributable to the editings I had performed upon the default 'Glassified' theme .svg files. The 'Plix' theme installation could not have provided such an amount of transparency on its own, for it has since failed to provide such in two subsequent separate installs.
Therefore, I must somehow gain a better grasp of how theming in KDE4 as implemented in PCLinuxOS is actually implemented. I am thinking at this point that surely there must be some 'borrowing' from other theme-sets, and that such 'borrowings' may form the default basis for all subsequent theme application. Is that view correct? Or am I aiming my guesses towards the wrong direction entirely?
Apologies - apparently I was mistaken, for I've now changed the background to black on the 'testbed' machine, and the systemtray background still is not completely transparent anyway. *ARRGHHH!!!*
Why did they have to make it so bloody difficult? WHY??....