Whom does the verse address?
Radak: It addresses Bnei ha'Galus.
What are "Mishpat" and "Tzedakah"?
Malbim: Mishpat is Bein Adam l'Chavero; Tzedakah is Bein Adam la'Makom.
Why does it say that His salvation close to coming?
Radak: It will come soon if you will fix your ways. This shows that [not doing] Teshuvah is blocking the coming of Mashi'ach.
Malbim: This is like it said in the previous chapter - Chesed Hashem is always prepared. It never changes. It depends only on the preparation of the receivers, and according to their deeds.
What is Hashem's Tzedakah?
Malbim: He vindicates His creations and brings to them merit via Chesed, not based on letter of the law.
What is the connection of salvation coming and Tzedakah being revealed?
Malbim: Via the Tzedakah, he sends salvation to them. The verse depicts that the Tzedakah already exists, just you do not see it; it is covered from your eyes. Via Mishpat and Tzedakah, it will be revealed and you will see it, and then salvation will come.