They both "overestimated" their opponent. As was already mentioned in the comment section multiple times, mental fortitude decided the match - Kiriyama was ever so slightly stronger.
Nah. Had a "what if" at first, but then the "plot" point (literally figuratively) about concave nips kind of reaffirmed that there is no fuckery going on with Tepeste's gender. Just your regular "act more like a girl" thing.