I would not want to live in a fantasy world without a bidet.
But anyway, answers.
1. Coincidences happen sometimes. Don't think too hard about it. In-universe, it's named that way because Darius's ancestors discovered it and decided to name it after themselves. Out of universe... 😁.
2. I just kinda thought about how languages work and engineered an answer from there. Our brains being able to assign words to certain things is mundane to us but if you think about it a bit, it's very cool that we can even do that.
3. You'll find out in the future 😁.