What is "Yefe Nof"?
Rashi #1: It is a city that is beautiful Nof; Nof is foliage of a tree. Dunash says, Har Tziyon is called Yefe Nof because it is Har ha'Zeisim.
Rashi #2: It is a beautiful Kalah. In cities on the sea shore, they call a Kalah 'Nanfi'.
Rashi citing Menachem: It is [districts,] like "Sheloshes ha'Nafes" (Yehoshua 17:11).
Radak: There is no district as beautiful as it.
Radak citing his father: It is one of the seven portions into which the world is divided; there are seven Aratzos 1 . The portions are called Nafos.
Radak citing Shocher Tov: All say that it is beautiful. Even though "Tzor At Amart Ani Kelilas Yofi" (Yechezkel 27:3) - you said to yourself, but others did not say [that you are beautiful]. This is like people say - 'not like her mother said, rather, like those who live near her say.' Tziyon does not say so [about herself], rather, all say "ha'Zos ha'Ir she'Yomru Kelilas Yofi" (Eichah 2:15).
Malbim: Tziyon has all the attributes - the climate of the mountain is very nice.
Otzar Midrashim (Yetzirah, p.241): They are Admah, Tevel, Neshiyah, Tziyah, Cheled, Eretz and Gei.
Why is it called "Mesos Kol ha'Aretz"?
Rashi: It is due to "Yarkesei Tzafon"; refer to 48:3:3:1.
Radak citing his father: One who goes from one portion of the world to another gets sick due to the change in air. The air of Eretz Yisrael, and all the more so of Yerushalayim, is nice - even Cholim who go there are healed - "u'Val Yomar Shachen Chalisi" (Yeshayah 33:24).
What is "Yarkesei Tzafon"?
Rashi: It is the north side of the Mizbe'ach, where Chatas and Asham are slaughtered 1 . Someone sad due to Aveiros, he brings Chata'os and Ashamos and gets atonement, and leaves happy (Shocher Tov) 2 . Good comes via the Korbanos!
Radak: Tziyon is in the north of Yerushalayim - "v'Eshev b'Har Mo'ed b'Yarkesei Tzafon" (Yeshayah 14:13).
Radak, Sha'arei Teshuvah 4:13: This is like it says "Yerech ha'Mishkan Tzafonah" (Shemos 40:22).
Radak citing Shocher Tov: "De'agah v'Lev Ish Yashchenah v'Davar Tov Yesamchenah" (Mishlei 12:25).
What is "[Kiryas] Melech Rav"?
Radak #1: It is a great king. This is like "Al Kol Rav Beiso" (Esther 1:8). It is David - "Kiryas Chanah David" (Yeshayah 29:1).
Radak #2: It refers to Melech ha'Mashi'ach.
Malbim: It is the capitol city of a great king.