Why does tzofon have greater kedusha?
1. gezeras hakasuv
2. ramban. vaykra 1,11 refers to an earlier comment [i dont know were]
3. meshech chochma-tzafoon, Efer of yitzchak.
4. i dont have a R. Hirsh chumash available, that is probably where i should look
5. the shulchan is tzafon, kedusha of guf?
6. enemy comes from north.
7. why ask? (Brisker approach)
avraham berger, yerushlayim/kew gardens hills n.y./passaic,n.j.
I will just add a few comments to your question, which already has a few answers.
Rabeinu Bachye on Vayikra (1:11) hints at some of the reasons you stated above, and adds a Kabalistic approach. He also quotes a Pirkei d'Rebbi Eliezer which indicates that Hash-m wants us to work on "completing the northern end."
The Ibn Ezra (Vayikra 1:5) indeed mentions that the point of being in the north is to be opposite the Shulchan, but does not elaborate.
The Rikanti (Shemos 27:1) says that the main Kabalas Pnei Ha'Shechinah is in the north.
Rav Hirsh says that Tzafon is the side that represents Gashmiyus, and slaughtering there shows that we are sacrificing our worldliness for Avodas hashem. See the excellent work "Lehavin," a compendium of Rav Hirsh's comments relating to the Mikdash and Korbanos.
All the best,
Yaakov Montrose