The new wardrobe is part of the Collections screen.
World quests are the new model for max level questing.
Relics are items which are socketed into your Artifact, similar to how gems from Jewelcrafting function.
PVP Talents (or "Honor Talents") unlock at level 110.
Many cosmetic glyphs are still made by players with Inscription and can be bought and sold on the auction house.
The fundamentals of gathering Legion are the same as they've ever been.
Once you have your first Artifact and hit level 102, you'll get a quest from the same person who gave you your first Artifact quest.
I would be surprised if no one makes something like Master Planner for Class Hall missions.
After you've gone through the quest to unlock your class hall, you may find that, without the ability to hearth back, you don't know how to get back.
You can play through the entirety of the Demon Hunter starting experience, which will take you to level 100.