This shouldn't be a problem ... you're not the only person with this 'issue'.

Where do I fine a ds260 number?

https://ceac.state.gov/ceac/ is where you will find the form ... once you get a case number.

Adjustment of status application for my fiance in B1/B2 status?

He should not file the I-485 within 90 days of entering the US ... otherwise he can be accused of visa fraud.

My family and I will be doing a California-Mexico border crossing to update our I-94. Is this fine?

Go with an attorney ... although it can be done ... the CBP officers are not all that 'friendly' about 'flagpolling'.

What did the company's immigration lawyer say when you asked him/her?

Immigration proclamation question?

You should be fine. But, it is not wise to leave the US during this COVID-19 pandemic.

Yes, it indicates that some, but not necessarily all, checks have been performed.

Can I travel with my expired green card and extension letter i797 notice of action receipt to Pakistan?

This should be fine. The best thing to do is get an InfoPass stamp.

Can My Wife on H4 make a YouTube video as a hobby, not for earning? Will it be a problem when we go for stamping in India?

YouTube for fun is fine .... she should not do anything that might convert to money.

Uscis office said they have ordered a biometrics for me... is there other way other than mail to access the letter

Yes, you can print the e-mail and go in at the day/time scheduled. DO NOT GO IN EARLY.