With most of this I would concur. But I would leave the culling to nature, it makes a *much* better job of it than people do.
Breeding for resilience / disease resistance includes giving sick birds the opportunity to get better, to develop antibodies - some of which they can even pass on to the next generation via their eggs. Received wisdom on culling seems to recognize only innate immunity, perhaps because it's always so focussed on the short-term = short-sighted. You cannot tell which birds are resilient before they have been tested, or if you kill them before they have chance to show they can pass that test. (What doesn't kill you makes you stronger and all that.)