(1) A Russian author may choose how to present his/her name so you may in fact see abbreviations like "Вл." (Владимир) оr "Евг." (Евгений, Eugene) and such. (For instance one of Moscow theaters is officially called "Театр имени Евг. Вахтангова". Here "Евг." is an abbreviation of the founder's name and is rendered exactly in this form.) But this is a part of an artistic expression. (After all, the name may be a pseudonym, so also an artistic creation. There is, for example, "И. Грекова" where the form is chosen because together it sounds like "игрек", Greek I; this is a pseudonym a math professor chose for her non-math writings.)
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).
