Biometrics : Should my American wife be present?

I am in the process of getting my permanent residency. I was on a student visa, graduated and now applied for permanent residency. Should my wife be present for the biometrics, or will we have to come in later for the interview where they will decide of whether our marriage is legitimate? How long after the biometrics can I expect to receive my employment authorization card, as my current one expires in May.