1)
What is the meaning of "ba'Shanah ha'Hi"?
1.
Rashi: It is the year that Ya'ir died.
2.
Radak: That year they pressured and crushed them, and for 18 years they crushed them like that year. It should say 'u'Shemoneh Esre'; the Vov is omitted, like "Shemesh Yare'ach" (Chabakuk 3:11) and other verses.
3.
Malbim: (a) They were punished immediately (once they abandoned Hashem). (b) The severity of the subjugation was already in the first year.