Simple answer ... NO If you want to work for someone other than the employer that 'owns' the E-2 you need a work visa. Where they pay you is...

What can i do to save work permit

You need to hire your own lawyer. As for your work permit .. what is the basis for your current work permit?

No, if you were over26 when you entered the US, you don't need to register ... in fact, you can't register.

Can i apply for DACA 2020 ?

Sorry, the answer is no. CIS is not accepting new applications for DACA.

Adjudication?

It is fancy 'government-speak' for "we're waiting for a decision".

What documents do I need as a proof I have been physically present in the USA?

Pay stubs, credit card charges, rental/lease agreements, notarized affidavits, etc. Talk to an attorney via Skype ... just click on one of our...

Yes, you can return the 'stamped' forms along with a new I-485 and new medical exam (signed by an MD less than 60 days ago).

What should i do visit apply for an B2 extention or file for F1 change of status?

Actually, you will need to file BOTH. The B-2 extension is known as a 'bridging' application. Read this: ...

What can be done?

Are you a US citizen? Did he last enter the US legally, with a passport/visa?

Can I apply for a J transfer out while waiting for Employment Authorization from ongoing green card case?

Can you apply? Yes Will it be approved? No, probably not Why not? Because the J requires proof of non-immigrant intent ... which you can...