1)
What is moaning with broken loins?
1.
Radak: Anyone who moans over a great affliction, it is as if his loins were broken, and he falls amidst moaning.
2.
Malbim: He will mourn about Churban Beis ha'Mikdash - "v'Hatef El Mikdashim" (7), until his loins break amidst great grief.
2)
Why does it say "uvi'Mrirus"?
1.
Radak, Malbim: Moan with a bitter heart in front of them, so they will ask about what you mourn.
