How does Tefilin Shel Rosh show that Hash-m's name is on you?

Rashi: A 'Shin' and 'Dalet' are seen from the outside. This is most of a name of Hash-m.

Tosfos: The Dalet and Yud on the straps are not absolute letters. They are not considered to be letters of Hash-m's name Shakai, for above and in Megilah (26b), the straps are considered to be Tashmish (what serves) Kedushah, but not actual Kedushah. Everywhere, [the Dalet] is called only Kesher Tefilin [but not a letter of Hash-m's name]. We say (Shabbos 28b) 'only hide of Tahor animals is Kosher for Meleches Shamayim. What does this affect? ... Abaye said, the Shin on the Tefilin [Shel Rosh] is a tradition from Sinai! (i.e. obviously a Kosher species is needed for it!) Rather, it is for the straps. This implies that the Dalet and Yud are not considered letters of Hash-m's name.

Rif (on the Ein Yakov): 'Shin' (spelled out) is an acronym for "Shem Hash-m Nikra."

Iyun Yakov: We say in Berachos 6a that Tefilin is Oz (strength) for Yisrael - Hash-m Oz l'Amo Yiten Hash-m." "Hash-m Yevarech Es Amo v'Shalom" - because Goyim will fear us, we will have Shalom.

Tosfos: Perhaps it is because Tefilin Shel Rosh are more visible than of Shel Yad. We say below (37b) about Shel Yad "Lecha l'Os", and not a sign for others.

Did Moshe see the knot of Hash-m's Tefilin?

Rashi: Yes; He wears Tefilin, like we said above.

Iyun Yakov: A Midrash says that when Moshe asked to see Hash-m's honor, i.e. the Midah with which He conducts, Hash-m showed to him Kesher Tefilin. He hinted that He ties in back of Himself those on the right and those on the left - Midas ha'Din and Midas ha'Rachamim together. "U'Fanai Lo Yera'u" - My countenance of anger will not be seen alone.

What is above and below?

Rashi: Above is at the height of the head. Below is on the neck.

Maharsha: This is like I explained in Kidushin (66a) the three crowns (Avos 4:13). Keser Torah is Tefilin Shel Rosh, about which it says "Lema'an Tihyeh Toras Hash-m b'Ficha." It must be above, so Yisrael will be above, via the Torah. Chazal said (Horayos 13a) your crown is greater than theirs. The knot must be Kelapei Panim, so that via Torah, Yisrael will be Lifnim (in front of) the other crowns, like we say that a Chacham comes before a Kohen [Gadol] Am ha'Aretz. Regarding Keser Melachim, it says "Bi Melachim Yimlochu" (kingship depends on Torah, i.e. Torah is greater).

What is Kelapei Panim?

Rashi #1: Opposite the Oref (back of the neck), and not on the side of the head.

Rashi #2: It faces the inside, and the beauty of the Dalet is outside, like we say 'their beauty is outside.'