Yes, it was explained that Oiye-Ryuu (お家流 = O-Ie-Ryuu = Google Translate: House Flow) was indeed techniques passed down through great or families with standing history which matches the translation. Kuon also said it was known as "Otome-Ryuu". I was conflicted in naming it but I just had my ITH sub it as Inherited Style.
As for the ??? character, I was just throwing out an idea. However, do listen to that character's sample voices. He/she has one mentioning Kensuke has "good potential if polished" which I don't really have any other clue to apply other than the fact that he is on his road to potentially becoming some sort of ruler and husband of all daimyo. That character could might as well be Asakura Yoshikage on the dark side or some other party or antagonist.
I really do hope we get more SenKoi. I wanna see Date Masamune (just hoping it's not another loli adaptation). They did mention a lot of other Daimyo factions including the Date in the original game that we probably wouldn't see on SenKoi X so that's hope on my end.
As for who's adorable, I agree with Mari but I vote 10/10 for Kuu. Ayana and Suzume can be annoying sometimes, but what I really want to see-erm, hear is Karasu's voice. I wouldn't be surprised if she had some sort of husky onee-san voice as a gap-surprise-factor but that's just wishful thinking.
Am I the only one who wants to see Kiyo be part of the wife harem? I mean, to me she has enough character to be added as a main cast with her own CG event.