85989-4L Super Mario Brothers Kids' Action Figure Playsets, Dungeon Diorama Set, One Size

Does boo come with the dungeon set? I see it in the original picture, but not in the other pictures or descriptions.

Do the characters stand up well/pose well? People are saying they don't and fall over.

are these meant to go inside of a fish tank?

I want to put these in an aquarium. Do you think it will hold up?