1)
Which descendants of Chizkiyah will serve in Melech Bavel's palace?
1.
Rashi (from Sanhedrin 93b): Chananyah, Misha'el and Azaryah.
2.
Radak (from Pirkei d'R. Eliezer 52): Daniel, Chananyah, Misha'el and Azaryah. We find that they were in Melech Bavel's palace, and they were from Yehudah, and Nebuchadnetzar asked to take descendants of the kingship and the nobles (Daniel 1:3-6).
2)
What is the meaning of "Serisim"?
1.
Radak citing Sanhedrin 93b #1: It is literal (they were castrated).
2.
Radak citing Sanhedrin 93b #2: Idolatry was castrated in their days (all recognized that it is impotent).
3.
Radak citing Targum Yonasan: They were officers.