Is there scaling in place for songs without too many beats? (my song vs. Idolmaster 2nd mix) It looks like there could be, but...
... Are Super Lessons really just as effective as regular ones? I swear it seems like I get a little more from the super lesson than I do for the regular, and that's when both are maxed out. The biggest offender of this phenomena happened when I went from Lv. 2 -> Lv. 3 on the first lesson (regular), then from Lv. 3 -> Lv. 5 on the second right after it (super lesson). I suppose the numbers could've just lined up right, but I haven't yet shook off that feeling...
This is the only thing I know for sure: Yes, there is scaling for different songs.
However, I've also found that your unit's mood affects the voltage increase rate too. Case in point: after losing to RK if you do an audition and don't use any memory appeals, you'll find that you won't be able to get to your second burst appeal (normally you would be able to).
Mood also affects genre interest increase rate, and the amount of bonus points that's added to normal appeals.
Super Dance Lesson and Normal Dance Lesson gave me more or less the same rate of increase with Perfect+Bonus gauge, the reporter, AND the Dancing mood thing. So I'm not sure in your case if it's just the numbers lining up or what. Which week were the lessons done on?
The rest of your queries I have absolutely no idea. To be frank, Lives are so easy there's no way you could fail with or without Burst Appeals. Although if you really need the extra Hako Yure the JP wiki recommended saving your second appeal for the end of the song (which will let you do 10 more appeals) - which you should really be doing in normal Auditions anyway to get the highest score possible.
I don't even use Memory Appeals anymore as I find that I can get a better score just by using normal appeals most of the time. I'll fire one off only if the Audition's initial interest rates are disadvantageous to me (i.e. 0.90 for Vocals and Dance if I plan on doing Vocals and Dance appeals).
Only obstacles in the game I'm not confident about clearing are the special Fes. Which I usually skip by picking アイドルにお任せ and 全力で to clear. As long as my high score for a song is over 45,000, they'll automatically clear.
Anyone found any good strategies for high score? My max so far on 3.5 playthroughs is about 55,000. You need 65,000 to have a chance at clearing VESPERIA with お任せ.