The problem currently is that a previous patch introduced a much smoother paced leveling system, though it was definitely slower. Many actually enjoyed the tweak to the overall progression system but ever since patch 8.0 went live, many MMORPG lovers are reported that is unnecessarily difficult to level through some of the older content drops, which was an unintended side affect according to Blizzard.
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Try to gather up all quests for a dungeon before trying to queue up for it. Preferably pick up dungeon quests as soon as they are available to avoid getting them when you are over leveled. Dungeons themselves reward a good amount of experience due to the grouping of mobs, but the quests on top of that reward great experience and decent questing gear.
From my understanding, the world boss is always there when your faction controls the Warfront. Like other world bosses you can only get gear from him once a week. There are other world bosses in the zones outside the warfront and 1 spawns a week just like Legion. I’m not 100% sure that the warfront will be available on launch but I have yet to read anything that says otherwise. The quest also reset once a week as well. Think of Warfronts like old Tol-Barad
He goes on to say that the changes went too far, and that they have "no desire" to keep moving in that direction. The problem is they don't know how to fix it quite yet. Hazzikostas understandably says that they don't want to make blanket changes that miss the "real source of the problem," which is exacerbated at levels 60-80 when the leveling curve gets particularly punishing. The sky isn't completely falling though based on data: Hazzikostas says that leveling is 15% longer. In the short term they want to increase experience gained at these levels to soften that blow.
So this is all from my understanding but with the scrapper it seems to be that you get materials based on the type of gear that you are scrapping. I.E I got more ore from scrapping plate gear and more cloth from scrapping cloth gear. Trinkets, weapons, and rings give different types of material and I don’t quite know the layout for that. Personally I would just DE everything as an enchanter. I stressed how important it is to trade with other players to get the materials needed to do all 11 warfront quest and you will obviously have more materials to create the enchantment that is necessary for the turn in to make trades with.

Edit 20 It’s been a week since this post and a lot of people are still reaching out to me with questions which is fine. I have had a few different people reach out to me to help make YouTube videos based off this guide and more info in BFA which I’m more than willing to do. Whoever gets the videos up first I will link them here for you guys to enjoy.