There are a bunch of passives that increase chances of her getting horny each turn. Some of them have specific conditions to trigger(like after flaunting) and some don't have any condition and work always.
I don't remember any "open pleasure" skill unless you are referring to pleasure stance. I think it also increases chance of her getting horny instead of making her instantly horny.
There are no unique poses for when Karryn gets fucked while in a bliss state, only her face changes(ahegao).
"Unique cg" you are referring to is probably post orgasm bliss pose where she lies on the ground face down, but to get this pose she needs to be not having sex with anyone when she gets the bliss status, otherwise current sex pose she has continues.
If I am remembering correctly the only prone sex pose Karryn has is with werevolves found at level 4. I can't remember if it was activated by having anal or vaginal sex, perhaps both? I am not sure.
Voice lines are tied to her slut level and sex skills levels. Basically, you will hear different speeches the more sluttier Karryn gets.