I dont think that Nietzsche's philosophising corresponds to existentialism too well, I know he's been described as existentialist but he wouldnt have known the word or very possibly embraced it (although Camus rejected it too I think), I'm unsure about some of Nietzsche's outlook too because he was off his rocker when he came up with some of his ideas and that's a fact, it can be amusing to speculate when exactly he was on the basis of his theorising.
Its clear he felt that life was meaningless and tragic and only had whatever meaning individuals created or attributed themselves, its also clear that he rejected humbling and quietescent thinking, or what he perceived as such, and thought that both of these perspectives where grasped by superior men, his ubermensch, but is his theory that different from Confucious' repeated maxims or sayings about "the superior man thinks/acts" or "the way of the superior man is...", every system of thought will assert its own superiority in some sense, otherwise, if it supposes one is as good as the next, it is nihilism.
There's a great deal of what goes under the heading of existentialism which I think is bogus, its later day sophistry by pseduo-intellectuals and egotists, and it goes double for much of the wordy pretenders which followed, like structuralism, post-structuralism and post-modernism. I reached that conclusion by comparisons between Orwell and Satre and their writings, I gradually came to the conclusion that Satre was despicable and typified a lot of what made Orwell (and I think its a perrenial anglo-saxon trait in many ways, even if I find that strange for other reasons to do with scholasticism vs. the reformation) sceptical or hostile towards intellectuals.