Was kinda unsure what to make of 鏡張り. From what I could gather, all the walls in the room are mirrors? I guess so you could...enjoy your own show.

So you invite Kokoro to a love hostel, and you get a special dance? Sounds good.

Kokoro's been getting addicted to human pop culture from the Outside, I'm guessing?

Sounds like she is referring more to the stereotypical mirrored ceiling that is normally above a rotating bed. Like the Palms Casino Resort's Hugh Hefner Suite in Las Vegas.