Does anyone know of a definitive list or database of edible plants, animals, insects etc.?

Answer 1

Tom Brown has info for you. His survival books are excellent.

http://www.trackerschool.com/

Consider Tom Brown's Guide to Wild Edible and Medicinal Plants, available on Amazon

Answer 2

All birds are edible plus their eggs.Most mammals are edible
all fat snakes are edible (cooked or roasted) Leaves of sweet
potatoes or beans bee grubs and wasp grubs are edible