Why are the loaves called "Lechem Panim"?
Rashi #1 and Targum Onkelos: Because the two sides of the Lechem ha'Panim were vertical 1 like two faces that could see the sides of the Mishkan. 2
Rashi #2 (in Pesachim, 37a) and Hadar Zekenim (in Pasuk 23): To teach us that the Lecham was a Tefach thick, because "Panim" always implies at least a Tefach.
Ramban #1 (citing Ibn Ezra) and Targum Yonasan: It is so-called with reference to "Lefanai Tamid" later in the Pasuk.
Rashbam: It is an expression of Chashivus - Bread that is fit to place before princes. 5
Refer to 25:29:1:1. See Ramban, who equates this interpretation with the definition of Lechem ha'Panim presented there (but not according to the second definition - Refer to 25:29:1:2).
See Torah Temimah, note 34, for more details.
Refer 25:24:1:1*.
As the Gemara says in Bava Basra, 28b 'Someone who wants to become rich should turn to the north'.
See Rashbam.
What is the definition of "Tamid"?
Rashi (in Tetzaveh, 27:20): It means 'from Shabbos to Shabbos'. 1
Menachos, 99b: 'Before they removed the old loaves from the Shulchan, Kohanim had already placed the new loaves, 2 in order to comply with "Lechem Panim Lefanai Tamid!" 3
Refer to 27:20:7:1*.
As if they were using the new loaves to push off the old ones. See Torah Temimah, note 36, who elaborates.
This opinion interprets "Tamid" literally. See Torah Temimah, note 36. The Gemara in Chagigah learns from "Tamid" that, on Yom-Tov, when they would show the people the Shulchan with the still hot Lechem ha'Panim to the people, they would announce 'Take care not to touch the Shulchan, since (due to the fact that the Lechem may not be removed) it cannot be Toveled!' See Torah Temimah, note 35.
How was the bread arranged on the Shulchan?
Hadar Zekenim (in Pasuk 23): Each loaf measured ten Tefachim long and five wide; when the ends was folded, it measured five by five Tefachim. The two rows of six loaves each were placed side by side on the Shulchan. Their width filled the length of the Shulchan, and their length, its width.
