#2 - May 18, 2018, 2:47 p.m.
Hey there Calix,
I cannot really answer question 2 as that is somewhat depending on what you hope to get out of it. If you just like to have professions with all (or as many as possible) recipes unlocked, then the quest is worth it of course. :)
As for making your own Crown, that would indeed have to be a new craft. To complete the quest, you are actually creating an Imperial Crown that is tagged as a quest item and so you don't get to keep it. Only after completing the quest do you get the real recipes for them.
With Battle For Azeroth on the horizon, you may be able to pick up the materials cheaper as time goes by though, so you can always keep an eye out on the Auction House.
Good luck with the Jewelcrafting business. :)