What is "[u'Fesach ha'Tzela] la'Munach"?
Rashi: The opening of the outside cells is to the empty place in the corner, like I explained (refer to 41:9:3:1).
Radak: The cell opened to an empty area in front of the cell.
Malbim: Each cell was divided into two. The wall in the middle was called Munach. "Munach" includes the wall between cells by the Bayis and cells on the outside, and also the interior of the outer cell. Yechezkel saw that the opening of the cell by the Bayis (which is called Stam Tzela) was open to the Munach, i.e. the cell next to it on the outside.
Where exactly were the openings?
Refer to 41:11:1:1-2.
Vilna Gaon: The north cells opened [to the Munach,] to their south, and the south cells opened to their north.
Malbim: There was one opening in the north, and one in the south. The verse did not say where they were, nor where is the opening of the outer cell to the outside. However, we can deduce that the opening had to be in the cell opposite the Ulam in the east, for a Beraisa (Zevachim 55b) teaches that there were two openings in Beis ha'Chalifos, eight Amos tall, to permit eating Kodshei Kodoshim and Shechitah of Kodshim Kalim in the entire Azarah 1 . Beis ha'Chalifos was opposite the Ulam. There was an opening from the Ulam to the cell by it, and from the cell to the Munach (the cell towards the outside. We learn from "u'Fesach ha'Tzela la'Munach" ? surely the openings were opposite each other! This was Machshir the entire area free of cells, until the wall of Chatzer ha'Penimi (10 Amos). We do not find Beis ha'Chalifos in Bayis Shelishi. [In Bayis Sheni,] the Ulam extended 15 Amos past the Heichal on each side. Here, the cells were from the western wall until the end of the Ulam's wall. From the cells until the wall of Chatzer ha'Penimi was 10 Amos, both opposite the Ulam and opposite the Heichal. The previous verse taught about chambers in Chatzer ha'Chitzonah near Chatzer ha'Penimi, to teach that these openings were Machshir also those chambers.
Malbim: We learn from "U'Shchato Pesach Ohel Mo'ed." (The Heichal, or at least the Ulam, must be open at the time of Shechitah; there may not be an obstruction.)
What do we learn from "Pesach Echad Derech ha'Tzafon u'Fesach Echad la'Darom"?
Radak: A cell in the north had one opening, and a cell in the south had one opening. The cells in Bayis Sheni had multiple openings - one to the cell on the right, one to the cell on the left, one to the cell on top, one to the Mesibah (that ascends to the top cells), one to the Pishpesh (minor opening), and one to the Heichal.
Vilna Gaon: Refer to 41:11:2:2.
What do we learn from "v'Rochav Mekom ha'Munach Chamesh Amos"?
Radak: Around the empty place was five Amos wide.
Malbim: The width of the interior of the outer cell was five. It already taught that the width of the interior of the inner cell was four (verse 5). The outer cell is called Munach, for it was added and placed on the Bayis. Each wall of the cells was five Amos.
Where is "Saviv Saviv"?
Rashi (9): [The Munach] is not in all four corners, like the simple meaning. Rather, it is on both sides ? the northeast and southeast corners.
Vilna Gaon: The Munach was five Amos wide, on both sides,
