What is the significance of bringing a rock?
Rashi: There are no rocks in Bavel, only bricks ? "Havah Nilbenah Levenim." 1 Angels brought a rock from Eretz Yisrael. If Hashem stipulated with Ma'ase Bereishis that the sea will split for Bnei Yisrael, the fire will be cooled for Chananyah, Misha'el and Azaryah, and the lions will not harm Daniel, He did not stipulate that throwing a rock 2 or weapon will not harm. The king said, I cannot remove him from the lions ? it was already decreed. Be careful that man not harm him 3 ? if the miracle will come, it will come!
Malbim: People should not mock and insult Daniel.
I.e. the continuation "va'Tehi Lahem ha'Levenah l'Aven" teaches that they did not have rocks. (PF)
Rashi said that there are no rocks in Bavel! Perhaps there are no big rocks that can cover a pit, but there are small rocks that can kill people (but not enough to build a tower from them). (PF)
The king was concerned lest others think that even if Hashem will save him from the lions, perhaps he will not save him from people. Before, no one would dare murder the king's beloved. However, now he was Chayav Misah! (PF)
What did he seal with his ring and the officers' rings?
Rashi: They may not move the big rock, in order to cast rocks on him to kill him.
Malbim: People should not say that they [moved the rock to] gave much meat to the lions, and therefore they did not eat Daniel.
What is the meaning of "Di Lo Sishnei Tzevo b'Daniel"?
Rashi: His desire will not change, i.e. they may not harm Daniel against his will.
