Dude, I am so sorry. I keep forgetting to watch this. Darn I'm like 4 episodes behind. Anyway, I just finished 5 and am starting on 6 while typing this. I should be up to date by the end of the day.
(I keep thinking "Darn it, FuniOP is going to kill me for missing this again.")
Anyway, episode 5 was like something you would see in a horror movie. Not like that's a bad thing.
EDIT: Yamagami is Ka-Wai-Ii! With a capital "K." I think today's Gainax reference was that she was totally channeling Yoko when she went all badass at the end of episode 5.
EDIT2: You know, the OP is really good, but it is really depressing when you actually read the lyrics.