Question

What pronoun would you use to address (speak directly to) someone you would call Mr. or Mrs.?

Answer 1

Mr = señor
Mrs = Señora

Pronoun he = el
pronoun she = ella

if you also want to know:
Her/him (e.g. I want to give this to him/her) = Quiero dar ese a sigo

Answer 2

Usted.

Answer 3

^ They both know it.

If you're addressing someone, you would use "Señor" or "Señora," yes.

And if you want to address that same someone, by using the word "you," you would say "usted."

Answer 4

True. You'd use usted for formally addressing someone.