Going through Japan means you will be going through the Immigration and be inspected at the port of entry in California again.

Yes, you may apply at the U.S. Embassy or Consulate in your home country.

Issuance of a driver license and state ID is different from state to state. Please contact your state's agency (issuing state IDs) for further...

Please consult with an immigration attorney in private as your question seems a bit complicated and you might have more questions.

We need to know how your spouse last entered the United States (manner of entry like B-2, H-4, F-1, etc.).

It depends on what country you are from. Most likely, birth certificates would do. Some countries use other formats such as family registry, etc.

If you file your I-485 now, USCIS will reject it. You need to wait for your Priority Date to be current before you can file your I-485.

Unfortunately, no. You must be currently in a valid period of OPT to be eligible for the STEM OPT Extension. Changing your status from H-1B to...

I am assuming you have a Receipt Notice. Have you checked the case status online to see if the status changed?

You should wait until the decision of your H-1B Petition.