For one, she can just turn around and leave. The visa in her passport becomes a green card as soon as she enters. But the green card will not be mailed overseas. It will be sent to your home address in the USA.
However, as mentioned, without a US income and permanent residence by the spouse, her sponsor, aka you, her visa may be denied. Establishing that you have domicile in the USA is important. Ask any Canadian and the number of issues that a US spouse not living in the USA can cause at interview. The point of the visa and green card is to reside in the USA. I would plan for moving back before the interview. She has time after the visa is issued to enter and use that time to close up whatever she is doing at home before entering.
I do not know the answer to the second question, I'm sorry.
For one, she can just turn around and leave. The visa in her passport becomes a green card as soon as she enters. But the green card will not be mailed overseas. It will be sent to your home address in the USA. However, as mentioned, without a US income and permanent residence by the spouse, her sponsor, aka you, her visa may be denied. Establishing that you have domicile in the USA is important. Ask any Canadian and the number of issues that a US spouse not living in the USA can cause at interview. The point of the visa and green card is to reside in the USA. I would plan for moving back before the interview. She has time after the visa is issued to enter and use that time to close up whatever she is doing at home before entering. I do not know the answer to the second question, I'm sorry.