1)
How will nations go in your light?
1.
Radak: "V'Halchu Amim Rabim v'Amru Lechu v'Na'aleh El Har Hashem El Beis Elokei Yakov v'Yorenu mi'Derachav v'Nelechah b'Orchosav" (2:3). Goyim, their kings and their officers will go in the light of Yisrael.
2.
Malbim: They will go in the light of Torah.
2)
Why does the verse switch to "Nogah Zarchech"?
1.
Malbim: Kings are at a higher level; they will go in Hashem's light - "u'Chvodo Alayich Yera'eh" (2).