That's wonderful that your daughter is looking into joining a sorority. Joining Kappa was one of the most rewarding and enriching experiences of my college time. A reference is required to pledge KKG. The reference can be written by any initiated alumna or active member of Kappa, no matter where they are. (However, the active cannot be a member of the chapter your daughter is looking to join. Therefore, no current LSU Kappa could write a reference, but an alumna of LSU could.) The Kappa who writes the reference should include her chapter and initiation date on the letter. Also, at my chapter, multiple recommendations were accepted (I believe that is acceptable at other colleges as well), as long as the Kappas were close to the young lady going through recruitment.
In regards to the poster, I have never heard of that. It might be an LSU thing (in which case, you could contact the school's Panhellenic Council or Advisor to find out). The best advice that I could give a young lady going through recruitment would be to relax and have a good time. So many girls are absolutely terrified (I know, I was one of them), and they shouldn't be. If your daughter is herself, (that is, the charming, intelligent, and friendly young lady I'm sure she is,) I'm certain that she will enjoy the entire recruitment process and pledge a sorority in which she will develop life-long bonds of friendship and sisterhood.
I hope that helps! Please write again if you or your daughter have any more questions!