As to her body, don't get too attached to it as is. First, watch the behind the scenes of Man of Steel, and watch Cavill's jump from buff to can-man-get-that-buff?. But Cavill wasn't the only one to undergo this transformation. Faora-Ui, played by Antje Trau, also did the get buff thing. And she was under armor the whole movie. I love this little detail in films (not that Man of Steel was a great film) but this one detail was right. There's almost nothing that pisses me off in a movie more than action stars who've never thrown a punch in their life. Buffy went on for seven seasons and nobody showed Mrs. Prince Jr. how to slug someone. This, interestingly, is also circumvented in Wonder Woman choices... In addition to being Ms. Israel, she was also in the Israeli army for two years, which is mandatory, but I'll bet she knows how to fight, at least a little bit. That, to me, makes her a better choice than 90% of suggestions. Including my own suggestion... Which would be Missi Pyle. If she got the Man of Steel workout and was shown how to punch... She'd be awesome.
As to the costume, I've learned to trust modern costumers (unless they're also graphic designers [green lantern]). The X-men costumes, the Bat suits, the Thor upgrade, even Captain America's suit. All magically faithful and yet tasteful. I have a feeling it'll reflect thematic style choices of her character, because they've gotten better about that. If they go greek/roman, she'll probably have a greek/roman look. If they go alien, they'll go alien. But function will probably be a large contributing factor, as they've been doing lately. armor when they need it, and no armor when they don't. I'm gonna trust them for the next few years until they break that trust (or reignite green lantern).