Welcome to Midgard!
I’m working here on developing a Norse-themed world in which to run a game starting sometime this fall. At the moment I’m planning on using the playtest rules and starting at first level, but it’s still far enough off that those things could change.
To start, have a look at the wiki. I’m working on fleshing out the sort of stuff you’ll need to know to start thinking about a character. If you have any questions or suggestions, you can put them in Forums. I’d love to hear what you want to know more about. Jacob already made the good point that I need to leave some things to be discovered in-game, but there’s still a lot more front end stuff to be laid out.
A point of interst, I’m taking a lot of inspiration from the Norse mythology book I read all the time as a kid, D’Aulaires’ Book of Norse Myths. You might track a copy down if you’re interested. It’s great.