File form I-407 to abandon your resident status.

Normally one is issued an immigrant visa at a U.S. consular post, which is outside of the U.S. If a person is in the U.S. in lawful, nonimmigrant...

If you already got your green card, then you do not need to process overseas to get an immigrant visa. You should not file anything with NVC, but...

Yes, you can schedule the visa appointment even if you are in the U.S.

if you are admitted after being married for two years, you may get a permanent green card, and there is a high risk you will get instead a CR card.

Correct. You can include the biometrics fee with the I-485 fee.

It's not the same as an RFE. It means there is a document you must bring to the interview, or else they may give you a due date to submit.

You can use either a joint sponsor or household member. If your father's total income on the tax return is sufficient, you can include him and do...

You will need to be a foreign student to complete your OPT, since there is no SEVIS filing for domestic students.

This site is for U.S. immigration. You can contact the Canadian consulate or check online to see what you need to do to return to Canada.