I feel like the "no matter the cost" refers more to the individual then to others, so an Amazon would sacrifice her life to save another or to save the day rather then someone else. Which I think will come into play with Diana not giving up on Vanessa.
Minus the brainwashing I think Vanessa being so self-conscious about Diana is from the comics even if eventually she got over it. All they're missing is her being jealous of Wonder Girl.Likewise, the discussion about Vanessa becoming a supervillain is presented as some sort of inevitable family dynamic where the "perfect" sibling will "create" the bad sibling. I'm not buying that dynamic.
I get that. I don't think they're trying to say that Diana wasn't loved on Themyscira, just that Steve can relate to her on an individual level separate from her duty and position.I'm also really leery about the line that Steve is the first person to love Diana the person. I think it misses the take that Diana is the child of a thousand mothers. Her fundamental origin is that she comes from a place where she is loved, and she gives that up so she can help others.
Purple Ray is a nice start .I liked what they said about Themyscira being advanced while keeping a classical aesthetic, but it's tricky to do in practice, so we'll see how they manage the execution there.
It's interesting that it looks like she has both super-speed and the ability to transform into a more feral form in this.
We see Julia hugging Wonder Woman alongside Etta and with Steve in a shootout so I think she's still alive when Vanessa becomes Silver Swan. She probably tells Diana that Vanessa's fallen in with the wrong crowd.