Do I have to update USCIS with my new DS-2019

The Responsible Officer for the J program should take care of SEVIS updating ... talk to him/her.

If possible to re-file, it is usually cheaper/faster to do a new I-485 'correctly'. A 290B appeal can take several years.

How long will I 290b take to reopen our case?

If possible to re-file, it is usually cheaper/faster to do a new I-485 'correctly'. A 290B appeal can take several years.

This is not an immigration question, I'll re-classify it.

Can a B2 visa be extended in US during the US visit, like I94/ stay extension?

Although they can not extend the 'visa stamps' in their passports, if they enter before September they will be given 6 months, and their I-94 can...

If you are willing to pay the full $20,000 cost for one year, this might be possible. But, the law only allows for 1 year in a public...

Can I apply for I-485 when H1b extension application is in progress and my family'COS application from to H4 is also pending?

Yes, with the assistance of an attorney, this might be possible. Don't try to do it w/o professional guidance.

How long it’s take councilor processing interview at Dhaka, Bangladesh?

I agree with my colleague ... probably the summer of 2021 ... if that.

Does applying for unemployment benefits affects green card holders or when it comes to citizenship application?

Uber and Lyft drivers are self-employed and give 1099 forms .... thus, you can not claim unemployment because you can not 'lay' yourself off.

no No NO A million times no!!! Working, even self-employment like this is completely forbidden.