A sharp knife is probably the best holistic management practice. An ability to cull hens and roosters to keep the overall health of the flock is very important. Knowing exactly how many chickens you need and generally it is not a lot of birds and keeping to that number through culling is a very good practice.
Keeping your flock young, while keeping a multi generational flock also keeps your birds healthier. Older birds tend to have more issues, and decreased production. One or two successful broody hens is nice, but more is not necessary.
Not wasting feed, is crucial in saving costs. And recognizing that different times of the year, different ages of birds, different weather, climate and temperatures all effect the use of feed and health of the flock.
Good ventilation is probably the next large mistake. In an attempt to keep birds warm in cold weather, beginners tend to lock up the coop, after all, we have been told since childhood to shut the door! But good ventilation to remove moisture and fumes while not in a draft is going to give much healthier birds.
Space is also VERY CRITICAL. Too many times, chicks are kept in too small of space to keep them safe in warm, when they should be exposed to colder temperatures and space to exercise and get better feathers and strength while growing.
What often starts out as enough space for chicks, rapidly becomes not enough space for adult birds. Feather picking, bullying are both strong signs of over crowding and the easiest solution is a sharp knife.
I do believe, a good commercial feed needs to be the backbone of the feed, but outside grazing gives more flavorful eggs. I also firmly believe in clean water. Trust me, no animal in the wild or in 'natural' lifestyle is drinking water with ACV in it.
Probably not what you wanted, but these things have more impact on the overall health of a flock than the things you mentioned.
Mrs K