A card with the information that you can only link copy/mod items that belong to you to the set. The rest won't link and will not go into a rez box. Everything else on your list as well.
I would put in LM to all the major dance creators and that would cover the free ones too since they all offer them. As far as helpful information, I'm more of a hands on person so the notecard would probably have my calling card and definitely a builder's grid texture. I find it invaluable for keeping things lined up.