If the kit really doesn't come with rear brake line drop brackets, that's just stupid and yes, you should get a set. So long as you DO NOT get new shocks that are too long, you should be fine with your factory front drive shaft. IF you do, yes, you should be looking to get a new one. IF your lift does in fact yield MORE than 3" of lift, adjustable front lower control arms will allow you to set more positive caster and that will improve your handling at highway speeds. New longer lines are only needed IF you are sitting at 3" or more and have shocks that will allow you greater droop.
At bare minimum, new longer rears so that you can install your factory rears up front.