it means simply that Hinata was originally been created by the author for a mere fanservice purpose. Oppai means boobs. Japanese are really in love with everyone with boobs, at least almost of them....
And yes, the interview is reliable, a japanese guy (takl) posted its translation on NF.
Haha well m not surprised cuz either way hinata is just not important so nothing new.
Well after that Naruto said to Hinata that she was the only one who was always by he's side ( Chapter 615 ). He never told something like that to Sakura i find that weird because he spent must of his time with her... That makes me a little bit suspicious of who is more important for Naruto between the two in fact... 
What naruto said was nothing special, you forgot to include that naruto also thanked neji for being by his side too, remember he said "you too neji...thank you"
And I dunno why you think naruto never said anything special to sakura, sakuras his lover and he's done SO many things with and for sakura and expressed it not only in his words but also actions (and sakura to naruto as well)
~サ ナル~サク 4/3 The day he fell in love with her ♥ 豪傑 そて 勇婦 hero, great man and heroine, brave woman°°°★Official Top Ten overall NARUTO characters: 1. Kakashi 2.Naruto 3.Sasuke 4.Iruka 5.Shikamaru 6.Gaara 7.Sakura 8.Neji 9.Itachi 10.Lee★°°° <p>Best ofナル~サク