Re: Which route should they go with Quicksilver's costume?
There was (supposedly) a source, not necessarily a credible source, and the British thing was just conjecture on the part of the article's author, because Ronan was from the UK. If they were looking at Ronan, they would have contacted her already, and she wouldn't have shut down that rumour so quickly.
As for her looks, Wanda has had green eyes since '97 (though, they're colouring it brown now). They were blue prior to that, but just about everybody had blue eyes then because it was easier for the colourists. I won't comment on "elegant beauty" because that's somewhat subjective.
But regardless of how she appears in comics, we really shouldn't shrug off racebending. I realise there may be difficulty in finding a young Romani actors, but I hope they're at least looking at some darker toned actors. It's a bigger issue than just accuracy to source material.