What are "Duda'ei"?
Rashi: They are pots.
Radak: The Aleph is extra, like the Aleph in "Chamishim Lula'os" (Shemos 26:5). ^They are baskets. Also Yonason translates so.
What is the meaning of "Mu'adim"?
Rashi: They are prepared [Radak - to eat].
Who are "ha'Charash veha'Masger"?
Rashi #1 (here and Melachim II, 24:14, from Gitin 88a): They are great Chachamim who were exiled with Yechanyah. When one begins [to speak], all are quiet, like "Hacharishu Elai Iyim" (Yeshayah 41:1). Masger - all sit in front of him and learn from him - "u'Fasach v'Ein Soger v'Sagar v'Ein Pose'ach" (Yeshayah 22:22).
Rashi #2, Targum Yonasan: They are craftsmen and gatekeepers.
Radak: Advisors and Chacham.