Whether your girlfriend will lose her scholarship is a question for the provider of the scholarship. It is not an immigration question.

Based on the information you have provided; You may file immediately. There is no need to wait.

I suggest you allow an attorney to review the file. I have never heard of a 221g and months of waiting just because a single document was missing.

Ready for an interview means the processing at the NVC is complete. The file is now at the consulate waiting to be scheduled for an interview. How...

He is free to leave the USA. Whether he is able to immigrate to another country is based on the laws of that country.

Not sure. Consult with an experienced immigration attorney.

There are many reliable sources depending on the language. If you are fluent in both your native language and English you can do it yourself.

No. Applying for aid to attend school will not affect the I-864 and supplement to sponsor her parents.

Yes. She may apply for NATZ now. No need to wait any longer.

Entering the USA on a non immigrant visa with intent to immigrate is misrepresentation. Sharing your preconceived plan on a public website is...