1)
Why does it say "Anshei Bnei Adoneichem"?
1.
Radak: He does not refer to the entire house, rather, only your masters' sons.
2)
How much of this was in the letter?
1.
Rashi: Until the end of the verse was all in the letter.
2.
Radak: Until "Yizre'elah." "U'Vnei ha'Melech..." was not in it (the 'narrator' says so).
3)
Why does it say "Es Gedolei ha'Ir"?
1.
Radak: Im (with) Gedolei ha'Ir, there were 70. Rashi - I do not know how many were Bnei ha'Melech.