1. “Free Range” is still limited by fences usually and >99% of cows will not live in the way many people understand free range because it would be prohibitevely expensive.
2. The methods exist but are never used for the same reason as 1. Pigs in Germany for instance are suffocated to death with CO2 causing extreme - if temporary - suffering. Nitrogen is a bit more expensive which is why it isn’t used.
3. It depends. Discontinuation of happiness is one argument why killing is immoral, even if they are killed without direct suffering.
4. Is killing a cow the only way for families to live through winter (without hunger/malnutrition etc.)? Then I’d say killing one is the lesser evil. If a family has other choices that do not involve killing, then I’d say the moral action would be taking them.

There are various more - and far better articulated - reasons why killing is bad by the way. Here are some: https://philosophy.stackexchange.com/questions/67606/why-is-murder-wrong

Still, I believe it is hardly possible to reliably kill without involving suffering anywhere.

Though I would consider hunting to be the most ethical variant. It’s not even a battle when factory farming exists.