Thank you very much! It's nice to hear good things about my works since I have a very average opinion about everything I do myself :P
There is indeed another cave on the road to Aerzen, and it's on the map where you fight the warg bear. You need the key from the priest to enter the cave fully.
That's a good pickup on the Lily's quest. I've had similar sequence break bugs in the game before, but sometimes they just fly under the radar so to say. Out of sight out of mind kind of thing. :3
And for purchasable cosplay items... I'd have to do it in same way as in Noel's quest where he wears the "religious ritual garb", but on a technical level it's not impossible to start a quest by buying X item in a store. (I might have something already planned regarding Rose and maids)