
10-17 million years after the big bang, the universe was in a “habitable epoch,” where the entire universe was, on average, warm enough for liquid water to exist. Any rocky planet would have been warm enough to support life then, even if it was very distant from a star. The modern universe is extremely inhospitable compared to what used to be
No, it’s not. Life, by definition, must proliferate. Proliferation requires energy, which is at an all-time low in the intergalactic vacuums. Not to mention that there is literally no matter to use to proliferate with out there either. A form of life that could thrive in intergalactic voids would be in the realm of science fantasy, not any sort of theory that can be taken seriously.
No, lots of creatures evolve to *survive* low energy environments. The vast majority of even microscopic organisms slow down their metabolic processes and wait for energy to become available again. Energy and matter are the basic building blocks of literally all possible baryonic life, and there is no physical way that life could thrive in an environment without neither. An environment which, mind you, makes up the overwhelming majority of the universe.