The length of the post is fine. I expect that I'll be making posts of that length from time to time as well, and my last couple have been rather long since there was quite a bit to set up.

I'll take the Tanzo. Their main "selling point" for the Aroi family is that their lord is a smaller Daimyo that shares borders with the Aroi family. They cannot match the Aroi clan in terms of military might, but an alliance through marriage would clearly be beneficial to both of them.