Would $25000 worth of assets be sufficient to sponsor my spouse in Form I-864 if I am unemployed?

$25,000 is not at least 3xs the poverty level 1 guidelines required if assets are used for I-864 sponsorship.

A person not required to file a US tax return may so state and provide a statement of that for naturalization.

Parent information is often not a US resident or citizen on a US passport application.

Can we come back to USA 70 days completion after my opt was done if I have an I20 from accredated college ?

Absent the visa cancellation a student may travel on an unexpired F visa for admission with a new I-20.

Can my employer file an H1B while my I130 is in process for an Immediate relative.

An employer's H1B filing has no negative impact on an I-130 filing. Usually, maintaining H is a beneficial to I-130/I-485 filings

Can I file for H1B after the denial?

An employer may refile an H1B despite a prior denial. And, again if need. There is no limit. But, it would make sense for the employer to retain...

Does F-1/I-20 Status needs to be maintained until status adjudicated, after I-485 is filed?

F-1 I-20 status maintenance can remain a fall back if the I-485 is denied.

Does i275 form on my visa passport effect to study in Australia ?

If inadmissible for immigrant intent it should have no effect on a non-US admission.

My girlfriend is waiting for RFE resolution of 0-1 VISA, can she comes to US with her current ESTA?

A person with a pending O-1 petition may visit the US on ESTA.

I have a business since 2017 and I have an F-1 visa, how can I change my status through my business?

A growing business with a small investment may be a vehicle for an immigration status.