Yes, there definitely be an "issue" - that of "unauthorized employment", which will render you removable from the country.

Hi. I and me husband have EAD application in process and he is on H1 and me on H4. Can I travel india at this time for a vac?

Yes, you can definitely travel overseas while your EAD application has been filed and is being processed.

Will the processing time for ead opt be affected if the i797 has been returned back to uscis as undelivered?

Yes, this will inevitably delay the processing of your EAD application.

Can we go for stamping before 3 months expire of your h1b visa?

Not a good idea at all under the circumstances you described.

Any employee's name will do in this instance.

Is a call from USCIS legitimate telling me to wait for my decision on mail instead of going in person as told at interview?

Yes, that is "legitimate" and exactly how the Asylum Office conducts business.

For aos interview, use a copy of my current passport?

A copy of your passport should be OK, however, make sure to bring your original birth certificate and translation, if applicable.

What choice should I make?

Each option/plan you suggested is feasible, however, the fact that you overstayed 3 years in Australia could come back and hunt you when applying...

Can I change ead based on eb3 visa?

There is no such visa as "EB-3." Your eligibility to apply for a new category EAD depends on whether or not you are eligible to apply for...

My son has approved for green card for three years ago , but until ,he hasn't yet the visa ,what should I do?

Have considered working with an attorney on this matter?