Few questions regarding the Gold Edition and the Game

Hello, I have few questions regarding the game.

1. I received 200 Helix after finishing the prologue, but I think someone mentioned in some video that the Gold edition also receives 500 more or that you get 500 when you finish the game? Is that correct?
2. There was suppose to be a (daily?) battle with a God but I am unable to find it - is that unlock further in the story?
3. What is the max level that you can achieve with Bayek? Is it 40?
4. What are the Carbon Crystals needed for? Early game does not seem to be of use.

Thanks for any help