Persian Cat has answered your second question.
I take it that what prompts your first question is the presence of two ands—why does the writer say “A, B and C, and D?” instead of simply “A, B, C, and D?”
This may not admit of a constructive answer, because what is in play here is a matter of literary (or would-be literary) style. I suspect that what the author intends us to understand is that something or other is full of A, B, and C — and, on top of that, D. If that is the case, I feel he would better served by using a dash instead of a comma before the second and, thus:
For Hemingway, the world was defined by strife: full of chaos, moral decisions and ambiguous moral boundaries—and inevitable pain.
In any case, it’s a pretentious and unconsidered sentence. Semantically, the full of phrase is probably meant to describe the world. Syntactically, however, the colon after strife implies that the phrase describes either strife or full of strife. Certainly the reader is led to expect that what follows will somehow characterize exemplify strife, but, alas, it does not: neither the strife by which the world is defined nor the striving parties are ever identified.
This is the worst sort of impressionist criticism: a string high-flown abstractions which sound as if they must mean something which you the reader are clearly not smart enough to understand, when in fact it is the author who is not courteous or craftsmanlike enough to put his thoughts in an intelligible order before laying them before you.