Yes, we are much beter off getting food from cows and chickens as well as from the ground.

It really depends. If you're out in the wilderness and it's an incredibly important matter, then yes I'd say it is somewhat justified. However, for most people living in modern society, I don't think it is, there are non-animal alternatives for pretty much everything. Killing animals when you clearly don't have to isn't justified.

In terms of survival yes, of course yes. But there is a difference to kill a animal for use and just to abuse/misuse it. I think we should use all of the resources that each animal kill gives us, the hide, the blood, the meat, the bones and so on, and not to waste it for one singular reason. I feel we should take only what we need from nature and not to go as far to ruin life for other animals or to hunt them to extinction. A point i would use is with the whales. We almost fished them to extinction all just for their oil and blubber because we got greedy. Everything we need comes from nature and we should treat it with respect and not to take it for granted. We should kill to survive and maintain ourselves but not for sport or boredom and certainly not because we can.

I couldn't really say self preservation is wrong. It's the one thing I believe we are truly meant to do. If ever there was a purpose to life, that would be it, self preservation.

Killing animals for ourselves is cruel, but is bad same as good. It was always right to kill animals for food, it developed for decades and became our moral right to feed upon killed animals for our sake. The tragedy is when animal murder is committed for trivial reasons like fashion (ferret/bear wool). But that's the circle of life. We humans use animals, animals would've use humans for nutrition as well. But certainly being ignorant and feeling no passion towards animals we kill is wrong.