Well tried the game and... I will give the only feedback that I can give.
-The first brat in the game I just couldn't help but slap him, in fact I think it was too much to add that scene in the middle of the class without anyone noticing it. Slapping him was the way to go.
-For now the only stat is intelligence, I truly hope that it changes in the future, the best thing would be a page for stats and your relationship with people, depending on what you want to do you may want to add quite a few different stats, just from your initial idea I think a few stats like: dominant/neutral/submissive, corruption, sluttery and intelligence would be appropiate, but perhaps a stat like strength could be useful to prevent rape and things like that.
*Dominant/neutral/submissive: Basically your attitude in general, a submissive character tend to be pushed around and a dominant one may impose their will on others.
*Corruption: An uncorrupted girl may even shy at having sex, while a fully corrupted girl would be willing to have even some of the weirdest sex acts, perhaps she even finds boring normal sex?
*Sluttery: How much of a sex addict she is, having a lot of sex increases it, having low sluttery let's you more in control of your character in things related to sex, even more she won't have sex with other people than her partner, high sluttery will make her horny and she won't be able to refuse many indecent propositions.
-About characters a few that could be expected would be a female bully, it's quite versatile, she may just bully you by stealing your clothes or things like that or she may even want you sexually. A slutty girl can always be appreciated too.
-About fetishes first of all I will say that there is a difference between avoidable and optional, avoidable means that by meeting the requirements you evade it while optional is when you directly choose if x happen or not.
-Questions more related to the fetishes would be how will you manage most of them, for example transformation the first one that people will think is the MtF or FtM, basically sex change, however it could be related to just getting a dick for the girl or breast expansion for example.
-Related to Nice Time for Roo here is a recommendation, if you add it then add stats for the other characters and make the game more event based, for example imagine that the MC is going out with a boy, but there is a female character interested in that boy and she is trying to seduce him, rather than a closed storyline it would be better for it to be based on the relationship level of the character (with you and the other girl), his moral and his fetishes. The advantage of it is that even if you got the boyfriend stolen it would be possible to get him back again or focus on another character, on this line it would be good that the NPC's would develop relationships with each other naturally.
Well here are a few points that I would recommend to consider. For now the game is kind of... empty would be the word, and out of 2 characters that I have seen I have slapped one.