H1B is employer specific so working elsewhere with a U visa EAD violates H1B status

Keep records of the reason for overstaying. A nonimmigrant who overstays for not more than 6 months is not barred from returning to the US.

Sorry to hear about your wife. Here are the instructions on requesting expedited service:...

Withdraw the I-90 and file an I-751. Work with an immigration attorney

How can I update i-94 admit date after passport renewal? Go to the CBP deferred inspection site to get it corrected

Before you can apply for a K1 visa, an approved fiance petition is needed. After entring the US on a K1 visa and after getting married within 90...

The US embassy may ask for the W2 for the most recent tax year. In any case, a joint sponsor can be provided

Changing from R2 to F1 will not adversely affect your father's Special Immigrant petition. Work with an immigration attorney.

Can I and my sibling both travel together to USA? ...

Processing times vary as each case is unique. You can check approximate times here: https://egov.uscis.gov/processing-times/