2.I've never thought that there was a fact in Naruto world in which old ninja can't be badass.
3.Maybe Kabuto didn't know how to read the part of Izanami's explanation.
4.I understand this. Actually it bothers me,but not as much as how it bothers you. Your becoming this way because you're expecting too much from Kishi. Honestly,I've never expected a single thing from Kishi. All I want is to keep reading his manga,and it's good enough.
5.War is something big and we all know this. Then just imagine, how do you think we can see every single fight of soldier in world war II? (I mean,our real world war II). If you were the mangaka,how are you going to show each of the battle? Wouldn't you think that some people might get bored with the fight like Kimimarou,Chiyo who were died and defeated long ago. We already knew their powers so what else we can see from them? At least from the boring Izanami we get to know that Izanagi has a weakness.
About the main fight.. I'm afraid if Kakashi and Gai actually done nothing important during the 20chapters.
Dude,I understand. I'm pretty much just like OMG please THIS IS THE LAST ARC kishi should show us every single thing of fight between Naruto and Tobi but the hell 20chapters are only for babbling of izanami, rewind of their actions like cut that cut this again and again,a little stupid worthless drama and just to show us the emo sasuke's useless ambition.
But then I stop being crazy and think like this "Kishi knows how to play his characters. The thing he want to show us isn't the whole war,but the fight. And the real and important fight isn't even started yet. If kishi shows us the early fight of Naruto and Tobi,then middle and the last part would be boring. because the early fight is only naruto vs jinchuurikis. I know Kishi will impress me,sooner or later,today or next year,the moment will eventually come".