This is a broad topic. Briefly: The average existentialist would take for granted that science can explain the origins of the universe and its eventual fate. Physical cosmologists hold that the universe is governed by physical laws as distinguished from religious understandings of humanity and the universe.
That is not a question. Atheists view friends as friends.
Suffering and dying exist. Existentialism has no part in atheism.
Atheism is NOT A RELIGION. It has no rules. Those are given by morality. Every atheist has different opinions.
Peirce is a partial-existentialist, which is to say that existence is only 'secondness' in his metaphysics. Existence is involved in reality, which is thirdness (there are no categories higher: see, the Reduction Thesis). Firstness, the remaining category, is that of feeling, possibility. So, in a genuine triadic relationship involving all Three Universes of Experience, existence is but brute action-reaction, so that reality cannot be reduced to it. Materialism, reductionism, etc. are denied by his philosophy. Peirce holds an evolutionary view of cosmology.
because there is nothing but yourself
Jean-Paul Sartre.
Some recommended cosmology textbooks for beginners include "Cosmology: The Science of the Universe" by Edward Harrison, "Introduction to Cosmology" by Barbara Ryden, and "Cosmology" by Steven Weinberg.
That the human being is supreme, period
Martin Heidegger (1889-1976). Another answer is Nietzsche. This is the most often existentialist philosopher named as an influence on Hitler.
Journal of Cosmology was created in 2009.
Cosmology of Kyoto happened in 1995.
Cosmology of Kyoto was created in 1995.