Acid Base Reactions Followed by SN2

Hey guys,

Once again, I have a few more questions.

For the first one, I understand that the amine is deprotenated by the hydride nucleophile. But why does the oxygen end up attacking the electrophile in step two? Is it because we only deal with the major resonance structure and oxygen carriers the charge better than nitrogen? Or is it because the oxygen with a negative charge forms a stronger nucleophile?

As for the second question, why does the topmost oxygen attack the electrophile? Is it because it experiences less induction compared to the alcohol group, therefore making is a stronger base and stronger nucleophile?

What is the rationale for these questions? Are we trying to form the most unstable resonance structure in the first step and attack the electrophile with said structure in the second step?

I appreciate the help as always.