Playing Dohna Dohna, have a few questions.

Okay so, been playing Dohna Dohna, I'm about 13 hours in, right at the start of Chapter 8.

Spoilers warning I guess.

1) Does Defeating >!Lu Bu!< in Chapter 7 does anything? Like, does it trigger an event, give a special reward later on or anything? Asking because I used pretty much all of my POW+, DEF-, MP, etc items on this section, mostly thanks to that fight. If the only reward is the EXP I got from it then honestly I'll re-load and skip it.

2)Does Zappa and Tora affection increases after story events? I swear I had Zappa at like 800 then it's at almost 2k now yet Tora is at around 800 only.

3)How important is the Hustling part? I've been doing it on and off, mostly trying to do it on Hustle Appreciation Day or w/e its called and for the events for the unique girls.

4)Unique Girls, am I right to assume that every time there's like a "cutscene" showing random girls on X area talking that a Unique Girl spawned on that map? Also, is there a time limit to those or I can go and grab them whenever after they appear?

5)Unique Girls seem to do MUCH better than anything else I can snatch from any map, so far. Am I right to assume I should prioritize those with pills, MEN items and such? I've kind of adopted a "Any girl with less than B on TEC/MEN gets nothing and is tossed when broken" (Damn, it sounds horrible when I say it like that) strat.

6)Without spoilers, is there a time limit to the game? So far it looks like I can do as much dungeons/hustling as I want before advancing the plot. But don't want to get too carried away then be smacked with that I had to do X or Y before Day Something. I'm on Day 37 btw.

Lastly, any tips? I'm not trying to min-max or anything, just play normally mostly, however, I would appreciate if there's any "Try to get every Weapon upgrade level, 3,4, etc before doing X or Y" "increase X's Affection" "Don't waste time with Z" and stuff like that.

Absolutely loving the game so far!