1)
Who are "Yod'ei Shemecha"?
1.
Radak: Yisrael nowadays.
2.
Malbim: They are Yisrael. Hashem shows for them love and dearness like a father for his son.
2)
In what was did Hashem not abandon Dorshav?
1.
Radak: He was with them at the time of their affliction.
2.
Malbim: His Hashgachah did not leave them even for a short time.