What do we learn from "Bo'alayich Osayich"?
Sanhedrin 22b: A woman is like an unfinished Kli. She makes a Bris with the one (her first husband) who makes her a finished Kli.
Radak: Your Master makes you, and the One who made you will be intimate with you, for in Galus, other masters had Bi'ah with you - "Be'alunu Adonim Zulasecha" (26:13). The plural is used for honor, like 'Elokim', "Yismach Yisrael b'Osav" (Tehilim 149:2).
Malbim: This corresponds to the two matters in verse 4. You will not recall widowhood, because Bo'alayich will return you to your status. Also refer to 54:5:3:1.
What is the significance of the name "Hashem Tzevakos"?
Radak: Everything is in His ability; He is the Master of legions above and below.
Why does it say "v'Go'alech Kedosh Yisrael"?
Malbim: This name applies when Yisrael are Mekadesh Him via their deeds. You will forget the shame of your youth.
What is the significance of the entire land calling?
Radak: This is like it says "Le'avdo Shechem Echad" (Tzefanyah 3:9). All will admit to Him.