I know Esther is shown wearing a black coat in that photograph and there's a teaser with that coffin scene, but I thought I'd seen her wearing black quite a few times in the earlier episodes. In fact, I'd recently noticed that she's starting wearing other colours like that green gown and wondered if it signified a change of heart/attitude to life.
As for Charlotte's hair, it really does annoy me too. I can only assume it's supposed to signify her lower social status or inform us, if we hadn't worked it out already, that she's a free spirit crossed with a dimwit.
Oh...and I'll put a tenner on Mr Darcy, because the way things are going, I wouldn't be at all surprised....