The outfit is basically a one piece swimsuit, a skirt, shoes, and a scarf (doll versions of those things, in any case).
As for the ethics of changing the clothes of a doll that looks like Nanase, it only closely resembles Nanase when she's not inhabiting it, and more, um, "sensitive" features are lacking (almost as though it were a doll or something).
Personally, I like the scarf. I couldn't tell you why, but I like it, so there.
Commentary added for December 31, 2014