also, 6 should be ellos because you are speaking about multiple people (the phrase given to you translates to "your friends José and Paco"). you would speak about two boys using third person plural masculine tense- ellos.
7 should be él because usted translates to "you" (formal) which you would not use if you were speaking about the person.
usted and tú are both words for "you," so you wouldn't use them if you were talking about someone. you would use them if you were addressing someone.
