From my experience on the Beta as an enchanter/tailor, scrap every trinket (and maybe rings). Trinkets seem to always give expulsom and it's needed in the higher enchants. Scrap any cloth green drops for the extra cloth, but other gear and blues and purples disenchant for the mats. The scrapper seems bad at the return on some items. I'd scrap old Azerite armor and get some cloth and a bit of thread.
I defintely think at 118 you should go and do all four of these parts. These are required to unlock World Quests and probably take about 60-90 minutes to get through. If you do these whilst levelling (especially all in one go at 118) then when you hit max level you're ready to go on WQs. You can go finish the zones quests at your leisure over the next weeks/months or never even finish them if you don't care about questing.
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.