Filing two separate I-864 for a foreign wife and a 2 years son

If it is only you, 2 for the wife's I 864. 3 for the son's.

Can I Expedite my Daca?

Yes you can request the Agency to process your renewal faster.

What is the procedure after receiving an approved I601a ?.

You need to inform the NVC about the approval of I 601a and restart the process of having your interview at the consulate scheduled.

Query regarding L2 visa holder stay

Answer: No. The wife needs to file an extension of her status before the end of her current status. USCIS form I 539.

My green card has been misspelled, do I ask for a change of name on N400 even if it’s a correction, not a real change of name?

Depends. One would need to review that "misspelling" in the context of your case in order to offer a suggestion.

How long does it take to get approved with vawa?

Depends. You can review estimated (by USCIS) processing times on www.uscis.gov.

Once you changed status from F1 to G4 your OPT has become a distant past.

Applying for naturalization after EB2-NIW, and changing job soon after becoming a PR.

It should be fine especially if you continued to work in the field of NIW.

What ate the other forms We should submit together with the I-130?

I assume you are applying based on marriage. You should start by reading the information here:...

Do I need to get a waiver for the two-year rule?

No. Your waiver was already granted. You said it yourself.