Discharge after kidding is normal for up to 6 weeks, just like with humans. An off odor, lethargy, lack of interest in feed and isolation indicate trouble, but IME this is very rare in healthy goats.
The "bro club" is real. Bucks love to live together and form bonds with each other. Based on my observation, I think they bond closer than does, who tend to be "mean girls" at times. And yes, they *can* live together.
Selenium maps are not accurate to specific locations. Soil and forage testing or blood testing your animals is the only way to be sure of their selenium status. We map "deficient" and blood test "high."
If it has clean water and the ability to drink, a goat will never kill itself from dehydration. Stop measuring water consumption and trust that the goat wants to live as much as you want it to.
A three-sided shelter is better than a fully enclosed one. Goats have delicate respiratory systems and need clean air. Their coats will do the work of keeping them warm.
The best solution for lice I've encountered in nearly two decades of raising goats is: sulfur powder dusted topically. Cheap, easy, no long term side effects.
Goats and humans can have a symbiotic relationship. I don't force my goats unless they will die otherwise. They give me milk, I give them excellent feed, both parties willing.
When is it bullying vs. normal behavior? Goats shake off normal headbutting, but bullied goats will show fear behavior: cowering in the corner, extreme avoidant behavior such as not going to the feeder or shelter, and even sometimes shaking in fear.
Goats are browsers. They're built to work for food, reaching and moving and choosing. The closer we get to that in our systems, the happier and healthier they are.