You may check with the IRS for taxes. A request for evidence or decision will be issued after the interview.

You may contact USCIS if your petition is outside the normal processing time or wait for the renewal of your work permit

If USCIS does not request evidence for a new sponsor, you will need to provide documentation of the new sponsor at your interview.

You have returned so the extension is no longer required.

You and your spouse are required to attend the interview. If that may not happen you may want to reschedule for a later date.

All documents must be submitted together with the RFE. Additional information can be submitted but may not be considered by the officer.

You will need a joint sponsor. This can be an expensive process and errors will cause denials and additional money to reapply. You should consult...

I recommend you consult with an attorney to review your application and supporting documents to ensure all required information is included.

Processing times vary for each location. If additional information will be needed you may want to hiring an attorney to respond.

No unless there is compelling reason to travel there and a request should be submitted to USCIS for advance parole.