Lore, Settings, and Story of Battle for Azeroth

It looks like there are two major events that will kick off the Battle for Azeroth:

Teldrassil is burned (presumably by the Horde) and Lordaeron is invaded by the Alliance.

Now, setting aside what that will mean for the leveling zones (because holy crap, where do Night Elves and potentially Undead players go?) the major question that people are raising is: Who Shot First?

In Legion, we saw Genn Greymane and Sylvanas Windrunner skirmish against each other, but the world at large was totally focused on the Legion. It's possible that this is just an outgrowth of that conflict, but one would think most people on either faction would want things to settle down. Granted, Sylvanas is Warchief now, so the Horde might have been posturing for war anyway, but who knows?

The Alliance and Horde are going to have very different leveling experiences, with the Alliance heading to Kul Tiras and the Horde to Zandalar. At the level cap, each side invades the other, and so the two continents will open up for max-level gameplay.

Kul Tiras is ruled by four noble houses: the Proudmoores, Waycrests, Stormsongs, and one that I don't believe was mentioned. Jaina's mother, Katherine, is the leader of her house (holy crap, do you realize we finally have a mother-child relationship in World of Warcraft? Seriously, how many of these people only have dads?)

Kul Tiras is divided between three zones: Tiragarde Sound, Drustvar, and Stormsong Valley. Tiragarde is a large bay populated by sea-monster-hunters and has a pirate problem. Drustvar is cursed, with witches using death magic, and Stormsong Valley is a large, idyllic grassland that is being threatened by "Dark Forces" (represented by an NPC in armor that absolutely SCREAMS N'zoth cultist - tentacles and creepy eyes and such.) Also quillboars.

Zandalar, likewise, is divided between three zones. Zuldazar, Naz'mir, and Vol'dun. Zuldazar is the oldest city on Azeroth, ruled by King Rastakhan and threatened by "Blood Trolls." Naz'mir is a fetid swampland with ancient Titan ruins where you'll enlist the Loa to help you. Vol'dun is a vast desert where criminals are exiled, and you'll help a race of fox-people against evil snake-people.

Key characters in the expansion will be Thrall, Jaina, Sylvanas, and Anduin, and they've said they want to continue the story of Vol'jin, which... um... is a pretty interesting thing to do given that he's dead.

The first raid will be Uldir, the Halls of Control, which is an ancient Titan quarantine facility on Zandalar. Supposedly this will appear totally run-down and infested with evil slime monsters, unlike the generally clean-looking Titan places we've been to before.

We also know that Azshara will be a raid boss later in the expansion (not clear if she'll be the final boss - my money's still on N'zoth.)