All that had happened to him refers specifically to the difficulties that Mordecai has had with Haman.

The exact sum: the precise amount or quantity (see 3.9). It may be helpful in some languages to restate this expression as Good News Translation has done.

The king’s treasuries: see comments on 3.9.

For the destruction of the Jews: Haman’s promise of payment was for the purpose of bringing about the destruction of the Jews. Traduction œcuménique de la Bible, Biblia Dios Habla Hoy, and Parola Del Signore: La Bibbia in Lingua Corrente say “in exchange for the annihilation of the Jews.” In some languages it will be necessary to express an agent for the destruction of the Jews. This may be an indefinite “they,” or the role of the king may be made explicit: “in order for the king to cause them [or, people] to destroy the Jews” (see also comments on Septuagint in ESG 4.7).

Quoted with permission from Omanson, Roger L. and Noss, Philip A. A Handbook on Esther (The Hebrew Text). (UBS Helps for Translators). New York: UBS, 1997. For this and other handbooks for translators see here .