I hear you on those points as well. I always bring two IPADs and carry chargers . I Also have everything in hard copy in a big fat heavy binder. And on the hard copies I have the Prefomance list numbers so "everyone bear with me as I get set up for the next song" LOL I always worry about stuff going down even though its really never happened to me ----yet !
I saw that info in the BK7M manuel but really didn't pay much attention to it ( didn't understand it )
This 3rd grade level of explaining it worked for me even though I still don't understand the terms or why I'm putting this number here, BUT it works !