For the most part a clutch type lsd should last a good amount of time, if installed properly. You would have to see how hard you use your lsd and then change the lsd oil accordingly for it to last awhile. Let's just say I have a pretty good amount of experiance with lsd's, thanks to some weird problems with a 2way I had.
Oh the Drift Bible is not a bad video as some people make it out to be. It helps the beginner grasp the idea of drifting and some basic practice techniques that work surprising well for a beginner. It's also something good to watch when your bored.