1) WHERE THE LEFTOVER BLOOD WAS POURED
QUESTION: The Gemara records three opinions with regard to where the leftover blood (Sheyarei ha'Dam) was poured after the Haza'os were performed. Rebbi Shimon ben Yochai says that both the leftover blood from the Haza'os of the Chata'os Penimiyos (such as the Par and Sa'ir of Yom Kippur) and the leftover blood from the Haza'os on the Mizbe'ach in the Azarah were poured on the southern part of the foundation of the Mizbe'ach. The Gemara explains that although the verse implies that the blood must be poured on the western side of the Mizbe'ach when it says "on the foundation of the Mizbe'ach... which is towards the entrance of the Ohel Mo'ed (the Heichal)" (Vayikra 4:7 and 18), Rebbi Shimon ben Yochai maintains that the Mizbe'ach stood in the northern part of the Azarah, and therefore its southern side was opposite the Heichal's entrance.
This answer does not fully explain how Rebbi Shimon ben Yochai understands the verse. Even if the southern side of the Mizbe'ach faced the entrance of the Heichal, the western side of the Mizbe'ach faced the entrance as well! In what way does the verse imply the southern side of the Mizbe'ach as opposed to the western side?
(a) RASHI in Zevachim (53a) addresses this question. He says that perhaps Rebbi Shimon ben Yochai maintains that the Mizbe'ach was entirely to the north of the entrance to the Heichal. The only part of the Mizbe'ach in front of the Heichal was the one-Amah-wide foundation (Yesod) on the southern side of the Mizbe'ach. The western wall of the Mizbe'ach was not in front of the entrance to the Heichal at all, but further to the north. (This appears to be the intention of RABEINU CHANANEL here as well.)
(b) RASHI there (according to the understanding of the SHITAH MEKUBETZES #13) gives a second explanation. Perhaps the Gemara means that the southern tip of the Mizbe'ach was at the exact center of the Azarah (and thus it corresponded to the midpoint of the entrance of the Heichal), and the rest of the Mizbe'ach extended into the northern half of the Heichal. Accordingly, five Amos of the Mizbe'ach covered the northern half of the entrance of the Heichal. However, since the midpoint of the entranceway faced the southern side of the Mizbe'ach, that side was considered to be the side "towards the entrance of the Ohel Mo'ed," since people normally walk through the center of a doorway.
(c) The SHITAH MEKUBETZES there (#13) suggests (and proves) that the southern side of the Mizbe'ach reached the area opposite the midpoint of the entrance of the Heichal, as Rashi there says. He asserts, however, that the western side did not qualify as "the foundation of the Mizbe'ach... which is towards the entrance of the Ohel Mo'ed," because only five Amos of the western side was in front of the entrance, while all of the southern side was in front of the entrance. Since the southern side was "more" in front of the entrance than the western side, the leftover blood was poured on that side. (This also seems to be the understanding of the RITVA here, although a few words seem to be missing from the text.)