Re. the SP costume, I recall vaguely that the 2nd version of Nocturne was a suggestion from Coach Kumiko Sato. She suggested Mao to try out a deeper colour, so she'd look more mature. As for the final choice of picking 1st lavender version for Sochi and WC, the decision was probably based on a fan-voting held prior to Olympics.
Adding: Both Mao's SP/FS costumes @ Sochi were made by a domestic designer Tomoko Yasuno:
http://corazonltd.jp/yasuno/profile.html (Yasuno recently designed the costume of Jupiter 2.0, also the costume of Madame Butterfly this season). Interesting, in Yasuno's major work profile it quotes that she 'made' Mao's FS costume, but not designing it. So perhaps the original design of Rach 2 dress was not by Yasuno (but the lavender Nocturne dress was)
For the 1st question about 3F-2L/3L-2L, I thought that was a mistake by Eurosport commentators at the beginning of the season. They probably assumed that Mao would have her old layout with 3F-2L. But she's never changed her layout and was consistently using 3L-2L for that season. As we all know, Mao rarely make up for a jump (combination) mistake by adding a jump later on. And IIRC there was no problem with her solo 3F in SP at SA, so the 3L-2L layout should have been planned from the very beginning of that season.