I'm not sure what it takes to degrow, but I'm pretty convinced that there's lots of fat in our consumerist lives that could be trimmed away even without changing our daily lives meaningfully.
We will likely die for the lack of philosophy.
Mankind is not malicious, just malignant.
You might want to build an evil AI to swallow the fly.
I don't believe that one follows from the other. Humanity is part of nature. Humans are sentient, and groups of humans can decide that society and/or group systems should ideally behave in one way or another, e.g. that an economy can be organized in one way or another. Humans can also make models about the future, and make statistical predictions based upon current (sophisticated) understanding of how systems work. This sets humans apart from other organisms in nature which also operate un(or less)consciously in groups, such as ants, viruses, etc, and which have growth that is unchecked to the extent that resources permit.
Therefore, it doesn't follow that humans being part of nature implies that unchecked growth is inevitable; humanity recognizing that there are in fact finite resources on this planet which we're currently bound to, and attempting to tailor the systems which affect rate of growth to ensure sufficient runway with those resources, is a very pro-humanity thing to do. That is, some control of population and resource-usage with the goal of preventing resource and environmental exhaustion and subsequent mass calamity is a tradeoff that attempts to promote the longevity of reasonable living standards with the possible expense of some liberties and the possible reining in of some unthinking consumption patterns. That doesn't equate to misanthropy, any more than preventing a 3 year old from eating a fourth bowl of ice cream does.
Yes. This is how you bring down the cost of food to get it to enough people.
I'm not convinced that it quite extends to the entire spectrum of junk food, though. Processing oreos (feel free to replace with anything else) quite so much may bring the cost down, but I doubt that it actually does anything to feed people.