Hey Aeola.
The more levels that are consumed via rape or sex, the bigger the bonus that goes to either the PC or the girl. I figured out that usually if you rape, the bonuses go toward your own character. And if that leads to a pregnancy (sex=20), the bonus to stats goes to him. That was one area I was confused about when I played it. And, I'm not sure what the idea is to always reduce things back to level 1, but I figure as time goes on, the characters will improve.
About the town, some of those girls are generic combatants. The pictures look nice, but I think there might be other places you'll see the exact-same girls. At the end of the area, there's like three identical ninja girls you can battle with, and they all have the same CG. So, that's why I assume even though they seem unique, they're just enemies to fight and rape. I'm not sure how to recall the CGs.
Hey, have you ever managed to buy HP/MP for a girl? I've tried that option lots of times, but it always fails, mentioning something about not having enough +.
The 1-22 slots are like boxes you can put the girls into, for storage. I'm not sure why you would want to, but you can only have three active in your party at the same time, so maybe you just get too many to deal with easily. There's also CCS that the guy mentions in his blog, and it mean Character Change System. I'm not sure what it does, but I think you can eventually 'edit' girls.
I like listening to the music too. Not the ranch music though.