IME, simply crossing them may, or may not breed in the fungi resistance. And, certainly not in your F1 generation. You'll have to keep crossing and keep crossing until it has been phased out, and there will still always be a chance of it.
Or was that not the question?
1. I doubt soil quality will be effected. There will prolly be a large effect on the fungi, but maybe not so much on the worms. I guess that really depends upon what else the worms eat.
2. See above...cross breeding really takes lots of time and generations. In the end, it means better results. It may hurt the economy in the short run, but in the long run, more food is better.
