re: LSU Band...How difficult is it to make the drum line?

You're going to have to audition and compete. Prove you can march on up/down/off beats, prove your sight reading abilities, chops, know more than just a few rudiments, be able to play to a click track, and shite like that. Try outs probably take a week or so of daily show and evidence you can hack the routine (hack pun intended).