This FAQ has become such a problem for people. Answering to the question:
1. Yes, you can.
2. Yes, she can.
3. Just keep track of all the paperwork you have filed to make sure you can prove to the government that she was legally in the United States. She can leave before the biometrics.
4. Reasonable time. A few days to three weeks depending upon what is reasonable under the circumstances.
5. If she stays here for six months or one year, let her stay outside for at least a year otherwise the government can refuse her entry saying you have been coming too frequently. FAQ in detail...
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