Guild Wars 2

I cannot remember if you get the rewards for the story (season 2) if you complete it on multiple characters. Is it a one time reward per account or is it per character?

Also I finished all of season 2 but do not have a carapace chest box? Did I lose it somewhere?

1. Yes, you get repeat rewards doing them on multiple characters.

2. You only get the carapace chest boxes by doing the Vinewraith meta event in Silverwastes.