As for the lost book of Eldad and Modad, it gets even more interesting. There is a good case that this work is quoted (as scripture!) in the New Testament in the Epistle of James 4:5. Richard Bauckham makes the case in MOPT1. I'm away from my desk at the moment, but I will post the full reference when I have the volume in hand.
Visit PaleoJudaica daily for the latest news on ancient Judaism and the biblical world.