1)
Why does it mention Ehud's death after the salvation of Shamgar?
1.
Radak: There was not a full salvation in the days of Shamgar. He did not stop them from doing evil. It says only "also he saved Yisrael". It says (5:6) "bi'Ymei Shamgar Chadlu Orchos."
2.
Malbim: Yisrael sinned even in Ehud's lifetime, but his merit protected until he died.
