Main Story Question ( Spoiler Alert)

[Enkidoh]

Annie answered the first question well enough so I have nothing really more to add for that, but for your second question, the 'Thorne Dynasty' was a former rival dynastic line of Ul'dah's royal family which existed about two-three hundred years before the present day who were effectively usurpers to the throne (most interestingly, they were actually midlander hyur instead of dunesfolk lalafell like the current and legitimate Ul dynasty, as their family name suggests).

The Thorne dynasty have been referred to several times in the past in the game's story and content, for instance, the quest which unlocked Copperbell Mines early in the game referred to the Thorne dynasty as the ones responsible for enslaving the hecatonchiers whom rebelled and were sealed within the mines to die, and also during the lore behind the annual in-game festival 'Little Ladies Day', which resulted from the story of Sultan Baldric Thorne's daughter (Princess Edvya) who often tested his authority as a parent.

From what I remember, the Thorne dynasty only lasted barely a century before the Ul dynasty was restored as the ruling house of Ul'dah and effectively died out (at least, until Teledji discovered Nanamo's handmaiden Meriel was a distant relative of the family, and thus a new potential claimant to the throne).

Anyway, that's it in a kuponut shell - there was an old thread that went into detail about the Thorne dynasty and how it was connected to the current Ul dynasty, but that was before information appeared during quests in game, so it's now not really relevant.