2) like Spanish perro, but accent on the last syllable, "perró". I think Pierrault would add a "soft sign", Пьерро.
3) There's no equivalent of W in Russian, and different translators take different ways - either В (v) or У (u). E.g. I read two translations of Sherlock Holmes with Watson being Уотсон and Ватсон.
Really? That contradicts everything I've ever been told about the Russian alphabet. What's the difference between Перро and Пэрро?
Also, sometimes in borrowed words everyone writes Е like in the original but pronounces Э, especially in the Western part of Russia. IDK exactly the reasons, may be it's just disgust for the letter Э, may be it's Ukrainian and Belarussian orthograhy influence, where Е is pronounced like Э.
But a foreign author does not do that, of course. As far as I understand the algorithm is something like that: 1) abbreviate according to the language of origin; 2) see how this abbreviation will sound in that language; 3) represent this sound in Russian. Usually this amounts to looking up a previous decision on that name.
I think this is a common issue in cross-script translation.
(2) "Перро" should be more like "Perrault"; "Pierrault" would be "Пьеро" or "Пьер", more French-sounding.
(3) This is a custom. The sound "w" does not exist in Russian, so there is a choice how to represent it. Most often it is "в", but there is a tradition in rendering it as "у" if it is the first character. And it seems the choice changed over time, so Churchill is traditionally "Уинстон", but the cigarette brand "Winston" из "Винстон". In the middle of word it is almost always "в", but there are exceptions, such as "Хемингуэй" (Hemingway).
(1) If an author is named Vladimir, would the initial be "В" or "Вл"?
Usual English practice is to do initials purely by spelling. So Sharon Stone would be reduced to S. Stone, not Sh. Stone, even though no S-sound is present in the name.
(This is also the Chinese practice - Shanghai gets abbreviated SH, which feels appropriate until you realize that it's S for shang, H for hai.)
(2) How is Перро pronounced? Would that correspond better to Perrault or Pierrault?
(3) Why is Darwin "transliterated" with в rather than у?