It's not that formal, more of friends gathering to spend time together. Or tbh, I don't know, I've only been training iaido for such a short time I don't really know the people yet.
Food is provided by the host, and I think the BYO drinks is more because of people having different tastes.
Regardless, I was wondering about the traditions out of my own curiosity, not because it's necessary or enforced or anything.
