For such a complex case history, best to consult with an attorney in private.

F4 visa sponsorship?

Once the visa becomes current, you would need to provide financial support documents and proceed within 1 year of visa becoming available.

What do I do again after uploading all documents of joint sponser, yet it is still showing on the home page as unsubmited

You must also submit petitioners income information even if consign is needed.

Once I withdrew my petition, did that cancel out the I-864 support form I had signed? Or is that separate?

Yes the I864 would be void as well as the underlying I485 is not applicable with the I130 withdrawal.

My mum overstayed her visa can I still fly with her to Texas?

I agree with my colleague - wait for receipts before traveling domestically by plane.

No a new visa is not required and she should be able to enter using valid visa.

What happened If someone with b1/b2 visa marry with a green card holder, before entering to United states?

That cannot be the individuals intention to enter on a tourist visa to adjust status but s/he may visit.

I applied for citizenship online me and my wife on Sep. 28 2020 but I still didn't get appointnent for biometric.

USCIS may be using previously captured biometrics. Contact USCIS to inquire.

Have you EVER previously filed a petition for this beneficiary or any other alien?

It doesn’t appear that you ever filed a petition for this beneficiary or any other.

You can use the Avvo search tool to find an attorney who can assist.