first of all: thanks for the guide, i just started the game. and like you said:
The only problem is the quiz, which you have to play per run 2x. In the first run, the questions and answers are given in the spoiler. In the following runs you have to use the spoilers from the first run. Unfortunately the answers are inserted in the jpeg format, because I have found no other solution. If this is too complex, the original link to the quiz is included in the credits.
i only did the quiz two times so far and had massive problems finding the correct question/answers in the picture you provided. it just took too long since i'm not really good in "reading" Japanese (or rather memorizing those symbols).
even with pausing the game the time ran out on me twice since i had to re-check too often.
don't know if this is only a problem i'm having, but in case someone else isn't really good at it i made a text-version of the two quizzes in some kind of miniguide: http://ps3imports.or...ide-supplement/
i grouped the question/answers by easily distinguishable (for non-japanese people) things like english words or numbers in the question or answer and then sorted it by length of the question so you can better pinpoint the location.
at least i can "work" way better with that list plus you could search in that.... hope this helps someone else, too.
oh and btw: failing the quiz for D rank is harder than i initially thought since it's a 50:50 chance and letting the timer run out simply selects the currently selected answer. 
*edit*: done with game game, thanks again.
just some hints: you can use the scene skip feature (square for submenu and then triangle) to directly jump to the next choice. i was feeling bold and tried it, had no problems with any trophies, so everything unlocks normally.
indeed you don't have to S-rank or even D-rank everything, as long as the overall result is S,A etc for the endings. in fact i simply "gave" up on some of those late rhythm-games and only got A or even B on the S-rank route and it still was S-rank overall.
quiz: i personally found it way easier with the text-list i provided, but i guess some people may have a different opinion, so just try it out and see what works for you.
plus it seems that you get an S-rank on the quiz with 8/10, so you can make two mistakes.
I simply chose random answers once i got 8/10 right... since it's 50:50 anyways theres a good chance you even still end up with 10/10, but it's not necessary and shaves off a little bit more time (you basically just have to look up 8 questions instead of 10).
and i didn't seem to have much problems with the "hidden voices" thing. only cycled through all pictures twice until i got it.
just make sure to click on the upper right Heart (it even says "touch") whenever there is one. at first i thought it's basically just telling you what to do, but you literally are supposed to touch the heart there. this seems to be a special voice all the time!
the others are random, i just clicked everywhere until i heard at least three or four different voices and moved on.
the last picture seems static, btw. this widescreen one with all the guys. simply click on each guy once.
ok, guess that's it 