1)
Why did Shmuel ask "why did you ask me"?
1.
Rashi: You already asked live Nevi'im!
2.
Malbim: From the three matters you mentioned, you should know the answer! (a) Hashem veered from you, and gave permanence to the one who contests your kingship, i.e. David - "va'Titzlach Ru'ach Hashem El David...; v'Ru'ach Hashem Sarah me'Im Sha'ul" (16:13, 14). Also refer to 28:17:1:3, 28:19:2:1.
2)
What is the meaning of "va'Yhi Arecha"?
1.
Rashi citing Targum Yonasan: [Hashem] will help the man that you are his enemy. Arecha is a hater. This is like "u'Mal'u Fenei Sevel Arim" (Yeshayah 14:21), "v'Hishmadti Arecha" (Michah 5:13), "Chelmah l'San'ach u'Fishrei l'Arach" (Daniel 4:16).
