1. You would have to go on CEAC and click on add applicant and then add your child and upload her birth certificate. NVC will take some weeks to approve your child then you can pay for her D-260 and fill it and submit her required documents. Remember that your child DQ will be your new DQ.
2.NVC needs only your child’s birth certificate to approve her as your derivative so you just upload. But sometimes when it’s time for interview the consular officer can ask for childhood pictures with your child. But if your child’s birth certificate is not late then that’s fine