The constellations do retain a connection with their past however, feel free to alter the story that goes with the constellation.
Each constellation only has one specific power that will like tie back to what they are known for. Magic is limited for them on Earth though so they can only use it for a certain length before they need to rest in order to gain their magic back. 
Not really. This may change over time depending on what direction we take the role play in so we could include more about souls, realms, etc. 

Hopefully this helps! c: