2) Disappearing caravan sprite
As more people already wrote, same, can be repeated tho not always after the first try. All you need to do is get out of wiev range and come back. It appears to reappear more likely when there is an other caravan nearby. Can be fixed by breaking line of sight again, not always from the 1st try.
3) Quests
Sometimes there are more of the same quest in the city, they all are spawned event quests. You have to go to x and win battle. After finishing it, you can retake the other one or even two same quest and just get the reward on the spot. I do belive same goes for the “find spawned event” type quest. Works all the time.