the ctrl+k, if you don't have compiz or kde4 desktop effects using it, in kde control center you can remap this and many other keyboard shortcuts, as a example win key+d(show desktop, also called F13)
" My keyboard is an Advent, but works as a Microsoft Comfort Curve 2000."
mine is a standard keyboard(can't remember the name, PS2 standard perhaps) and i was successful getting all the keys on it
my specific requirement was my pc key, calculator key, multimedia keys(including audio player) and volume keys
as you say you can create shortcuts but for the functions i mentioned, this keys are very useful and i like to have my desktop as clean as possible