3. ellos. ellos means “they” as masculine and mixed. you put nosotros, which means “we”. this is incorrect because you are not a subject in this sentence, therefore making it impossible to be “we”
4. the abbreviation for “usted” is Ud. Maybe try adding a period afterward? (as it’s an abbreviation)
5. in latin america, the word used for groups is “ustedes”. it’s essentially the latin american form of “vosotros” and is used for either gender and either formality