Who doesn't like tsuntsun? I think that is an extremely cute character for a girl, hard on outside, soft on inside, both in the perverse and non-perverse way.
And yes, Ushio's teacher is Kyou. Talk about coincidences, this is going to be the worst one. It would certainly be the best if Tomoya tells Ushio about all the stuff in the past, like her throwing dictionaries at anyone who pisses her off, fighting with Tomoyo over questionable issues, etc.