it's not rude if you are the one who requested the meeting and are trying to back what you need to say up with research. You are assuming that the principal arranged the meeting whereas , I was assuming it was the parents. Yes, if the principal was running the meeting, certainly offense would be taken if you showed up with that type of material. The type of material being presented is what would dictate what type of material should be provided.

I second the sending a thank you letter.