What direction is the length of the chambers?
Rashi: It is from north to south, 50 Amos.
Vilna Gaon: It is from east to west. Refer to 42:8:2:2.
Why does it say "Al Pnei ha'Heichal Me'ah Amah"?
Rashi: It is from east to west, opposite the Ulam, Heichal, Beis ha'Kapores and cells ? 100 Amos. Radak (7) - the chambers occupied only half of this.
Vilna Gaon: On the side of the Heichal, the chamber was 100 long. On the other side (towards Ezras Nashim, outside) it was 50 long. After this, it was on a diagonal. The Geder was around the chamber, and bent where it bent.
Malbim: The chambers of Chatzer ha'Chitzonah opposite Ezras Yisrael, they were only 50 long. However, the chambers in Chatzer ha'Chitzonah opposite the Heichal, they were 100 long.