For a starting character, roll the 4 d6. You may reroll one result of “1”. You start off level 1, with one tier in Mythic. Roll for starting gold. Also, traits and drawbacks are open. Any other questions, ask the DM.
Yggdrasil bears nearly all races: almost any are fair game to play as. However, there are a few that make no sense given the setting: any reptilian races are pretty much screwed, so they are out. Also, androids are not a thing, so forget about that.
if its not an original race, ask the DM.
The only classes not allowed are Samurai, Ninja, Alchemist and anythign with a gun. Technologically, this is not an advanced setting. It also lacks any cultural exchange of great import. The hybrid classes are acceptable.