ok i had missed which set each card is in. So basically if needed for quests then grab one as late as possible, otherwise let them stay in the staging area.
Minor follow-up with placement of objectives: I would assume you move them with the card they are attached to (enemy or location) then when the attached card is discarded put the objective back in the staging area.
Correct. But don´t leave them in the staging area for too long....or the Dungeon Jailor might come looking for them