A Christian theory of government finds its foundation in this passage. There is no authority except from God. What authority is in place is appointed by God. Seems a lot of bad government is appointed by God! Authority should punish evil and praise what is good. It is not coincidental that this discussion of authority comes right after the discussion of vengeance and being overcome by evil.
Romans 13:8 is not about financial debt. Love is your primary obligation. Loving your neighbor fulfills every other law! So, a violation of any other command is also a violation of love -- two sins in one!
Because the day is near and the night is far gone, get rid of deeds of darkness and put on what fits light. Clothe yourself with the Lord Jesus Christ and literally, 'don't think ahead' about how you would fulfill the desires of your flesh.