Wow totally, she's part of the Cullen's now, so definitely. No ring because she has her wedding ring on. Well she should have the crest like a charm, so she can hang it on her bracelet that she got from Jacob. inayofuata to Edward's moyo and the mbwa mwitu charm :D
I think it`s a must! Like Alice alisema that part of being a Cullen is to be meticulously cautious , well-another part is having the Cullencrest. In my opinion she should have it as a coronet in her hair- I think it will suit her, as long as she becomes extremely beautiful, it`s pretty obvious her hair would remain as lovely
I personally hope she doesn't. Just because the Cullen's have been wearing it for centuries, and for her to just say " Oh, I'm in your family, i should get one." is not right. And too, just because she's in the family, doesn't mean she automatically gets one. And besides; her Bloodsucking husband would have gotten one for her before they were married.