To answer your question directly, 6 categorical PGY1 positions. This info can be found on either the NRMP website (under Data and Reports), or on the ACGME website (search Accredited Programs). Ill estimate that they interview about 60 candidates. 10:1 is the usual ratio at most programs.
Still, a little curiosity and diligence would serve you well. Try using the search function for dc2md. Once you see one of his posts on this forum, youll get the reference. If you PM him, he may provide you with the info you seek about LSU, and more.
Sorry I didn't see this earlier. I'd be happy to answer any LSU PM&R questions.
LSU has 7 interview days this year; 70 applicants in total. They're planning on filling 7-8 spots this year (still debating it from what I know). I know that all invites have been given out at this point, and we only have two more interview dates.
Like they others have said, if you have any other questions, feel free to PM me.