The 2nd is not strictly a question, but a defense of a recently deleted answer of mine. I will write it next assuming the answer to the 1st question is "yes". If it is "no", please tell me where to write it.
The answer I want to defend is this:
IMV, it is wholly relevant to the original question, which was "How can the doctrine of ancestral sin be justified in view of the Darwinian theory of evolution?"
The question itself has a problem, in that the legitimate concern is about the compatibility of a doctrine with relevant established scientific knowledge, not with any particular theory which may or may not be relevant and may or may not be confirmed by observations. And the established scientific knowledge which is relevant to the doctrine of original sin is the fact, established by extensive DNA sampling and sequencing, that all extant human males on earth are patrilineal descendants of one Most Recent Common Ancestor, usually dubbed y-chromosomal Adam, who lived 250-300 ka ago according to current estimations.
To be blunt, if someone is not aware of this fact, then they should first get a basic understanding of current genetic anthropology before making questions about how a doctrine can be justified.
Having set this straight, then I point out that this relevant established scientific knowledge does not present any challenge whatsoever to the doctrine of original sin, as it is enough to hold that Biblical Adam was either y-chromosomal Adam or a patrilineal ancestor thereof.
IMV, my answer is straight to the point and does not warrant deletion.