Why might it benefit your compost to add earthworms to the mix?

Better quality compost! Worm castings contain the worms' gut bacteria and mucus. These microbes and substances are very helpful to plants. Vermicompost has more nitrogen-fixing bacteria than conventional compost. Vermicompost helps make minerals in the surrounding soil available to plants more quickly.

1)0.14
2)80%
3)0.4

hope this helps