1)
What was Shmuel's objection?
1.
Rashi: I said (10:8) that I will offer the Olos, and not you. Radak - he knew through prophecy that Sha'ul had offered the Olah. 1
2)
What is "la'Mo'ed ha'Yamim"?
1.
Rashi: It is the beginning of the [set] day.
2.
Alshich: It is the seventh day from when Shmuel commanded him. Refer to 13:9:2:1.
3)
What was Sha'ul's answer?
1.
Malbim (11, 12): He gave the four reasons why he did not wait (refer to 13:9:2:2).