1. Pickpocket's shadow effect reads: Defending player discards 1 of his attachments. (Discard all of his attachments instead if undefended.)
It says nothing about control, so can you discard Local trouble?
I wish. Local Trouble is a Condition.
2. Harbor Thug reads: Forced: When the player whose hero has Alcaron's Scroll attached raises his threat, Harbor Thug engages that player.
So you can attach the scroll to Boromir (tactics), commit him to the quest, then ready him for +1 threat before or after the staging step and engage the 2 or more harbor thugs right away, not having to count their threat? Feels like that would make the setup threat a bit too easy.
Yes. Far as I can tell, you can ready and re-ready Boromir ad infinitum, barring you die from threat.