Hi Kev
To be honest I cannot remember where I found the facts about population control.
I do know that it was from a university in America who conducted extensive research about the subject and it was about 5 years ago when we started out.
Technically the worms are cannibals - a worm is approx 80% water - so when they die they break down quickly and then are eaten by the others !!
RE the roots, they will eventually go, but it will take quite a while. Roots are made so that they don't rot when underground, if they did, plants would have a hard time growing !
Ronnie