Orginally was planning that Shadow read them a story but I saw that so many times. Sooooo Hi since they feel they have a "connection with the stars/space" he teach them about the star sign's.
Shadow's clothes are during his time on the ARK 50th years ago. He have higher security cuffs that cancel his power completly. Maria was the one that give him the Ring that find his other half. Can be seen as casual attire.