1)
Why will you be filled with intoxication and grief?
1.
Radak: The intoxication is the grief that will fill you. The cup and wine are a Mashal for afflictions.
2.
Malbim: The first time you will be full of intoxication, but not intoxication of wine that gladdens. Rather, it is a drink that inebriates and finishes off intellect and fills [the person] with grief. The second time you will drink a cup of desolation; the entire land will be desolate. The third time you will drink the cup of your sister Shomron, which was the capitol.
2)
What is "Shemamah"?
1.
Rashi: It is desolation.