1)
Why is Hashem called "Yoshev Tziyon"?
1.
Rashi: They will sing so to Hashem when He returns to Tziyon. Radak - even though Tziyon was in the Yevusi's Reshus at the time, they had a Kabalah that the Beis ha'Mikdash will be built there. Tziyon is the head of Yerushalayim.
2.
Malbim: He is Mashgi'ach there constantly.
2)
What Alilos should you tell, and when?
1.
Radak: Wherever you will go, tell the wonders that He did with you.
2.
Malbim: Tell how He acts with you.
