Why did he ask to bring the Aron?
Rashi: He wanted to ask from the Urim v'Tumim [Radak - which were with the Aron.]
Why did Sha'ul want to ask from the Urim v'Tumim?
Radak: He wanted to ask about Yonason.
Malbim: He wanted to know what caused this commotion. He could not fathom that it was due only to Yonason and his youth
What is the meaning of "Hayah Aron ha'Elokim ba'Yom ha'Hu"?
Rashi: It is as if it says Hayah Aron ha'Elokim Sham ba'Yom ha'Hu.
Malbim: From the time that Mishkan Shilo was destroyed, there was no fixed place for the Aron. They took it to wherever Bnei Yisrael gathered, e.g. to Gilgal to renew the kingship (11:14), and Sha'ul took it with him to Giv'ah.
Why does it say "u'Vnei Yisrael"?
Radak: It means with Bnei Yisrael. This is like "v'Yosef Hayah v'Mitzrayim" (Shemos 1:5) - with Yosef, who was in Egypt.
