No contractor positions are permissible on STEM OPT jobs. You can only work as an "employee" and they can issue W-2.

All material changes require an amendment. Whether 50% changes in job duties in a new team is a material change requires analysis of both positions.

EB NIW may be an option depending on your strengths and goals. There may be other options as well depending on country of birth, nationality,...

It is usually not recommended to file for COS if a candidate is unable to maintain status in the interim. You will have over 5 months in the U.S....

I am assuming there was no substance (drugs, alcohol, other federally regulated substances) involved in any of these traffic violations and no one...

It will be best if she returns sooner and on this trip to the U.S. seek a re-entry permit for longer stays abroad.

If you file COS with future date but she losses job sooner, she will have to file again. I don't believed bundling the applications will help ease...

Document the purpose of travel to Australia. Hopefully it is for a vacation or brief travel and such reason.

You can apply for B-2, however you will need strong evidence of non immigrant intent. There are ways to document this however it varies with each...

Not sure if you understand "Change of address" requirements correctly. An alien is required to inform USCIS if they changed (moved from one...