Haha, thanks ^^ I just brought my graphic designer background cuz sometimes people keep looking for a plot or a history on some stuff that don't have it, cuz the work was displaying a overall idea and feeling mostly instead of a narrative. This tend to be done by very text focused individuals (like me, who did it a lot and who ended up stepping out of the designer production to write instead

)
Well... I just read the lyrics to feel more confortable on reading this, so, there are my thoughts about the pv/song:
Visually, it perverts the idea of "kawaii" with death symbols everywhere, causing a overall disturbing final result... Perverting the idea of kawaii is not anything new to jpop, btw, Ai Otsuka, Ayu and AKB48 are always doing it for example... Otsuka with sexual innuendos, Ayu by being agressive and AKB48 for being openly sexual. This time the twist is turning stuff morbid.
But the PV is very japanese on the way it is bizarre, the symbols, the disturbing images, the colors, the profusion of images, it's all very commonly the bizarre Japanese. It always common stuff from Harajuku fashion (from what I read and saw on internat as i never went to Japan)
IMO, when she contrasts kawaii and child like stuff with death symbols she is talking about growing old, the finity of the youth to the moment of your death, or the death of your youth, what is a recurrent theme on nowadays pop culture (the whole "let's party like there's no tomorrow" hedonistic thing most hot pop acts are doing for a while now).
The fat faceless white haired person being her old-self she is afraid of and avoiding, and the actual young Kyary Pamyu Pamyu being haunted by the death (and ageing) images, but at the same time, adored by her old self.
So, to me, it's a video (and the song also can be) about the fear of growing old, but knowing it's something you can't escape.^^
About the
Illuminati, they "are" a organization trying to bring the New Order or New Era to the world by controlling media, politics and organizations. This New Order being something like the apocalypse from the christian bible (no religion, only one nation, people having a mark on their bodies, etc.), and one of their methods is brainwashing though pop stars

So, if I'm not wrong, right now Madonna is their biggest priest on media, but Jay Z, Beyoncé and Gaga are also among the best ranked illuminatis... No need to say Ayu is one of the top illuminatis in Asia too

Illuminati obsessed people keep looking for signals of them on music videos, songs, etc...
edit: There are a lot of stuff on the video I can't really understand as I'm not Japanese, and I don't know the overall symbology behind colors and objects they use there... The Pink Kyaru for example, I don't know what pink means to japanese to the point of getting if her being pink on some scenes has a meaning or was just made to look cool. Stuff like the "bread" over here:
http://en.wikipedia.org/wiki/PonPonPon