Who washed the innards and feet of the Olah?
Ramban: The fact that the Torah only mentions the Kohen in connection with burning them on the Mizbe'ach implies that the owner is eligible to perform the washing. 1
Why does the Torah insert the word "Olah"?
Rashi: To teach to slaughter the Korban having in mind that it is an Olah.
What are the connotations of "Isheh"?
Rashi and Ramban: To teach to slaughter the Korban with the intention of burning it on the fire 1 completely on the Mizbe'ach.
Ramban:And not just on dying embers (Zevachim, 46b). Moreover, he must have in mind that the flesh should become burned to cinders (See Sanhedrin, 70a and Eruvin, 29b). According to an alternative text on the Gemara in Zevachim, it means that the Kohen should have in mind to burn the Korban on a fire of wood, and not one of straw and stubble
What is the significance of "Re'ach Ni'cho'ach"?
Rashi: It signifies that Hashem derives Nachas Ru'ach (satisfaction) from the fact that His will is carried out.
Ramban: It is the basic reason behind Korbanos in general. 1
Targum Onkelos and Targum Yonasan: It signifies that the Korban will be accepted by Hashem with goodwill.
To give Nachas to Hashem who commanded us to bring them.
What is the underlying reason behind Korbanos?
Ramban #1: Refer to 1:9:3:2.
Ramban #2 (citing Moreh Nevuchim): To counter the nations of the world, who worship the animals. 1
Ramban #3: To atone for one's sins, which one performs with Ma'aseh, Dibur and Machshavah. Consequently, the sinner performs Semichah (to atone for the aspect of Ma'aseh), recites Viduy (to atone for the aspect of Dibur), and burns the kidneys and the innards, which are responsible for a person's thoughts, on the Mizbe'ach (to atone for the aspect of Machshavah). He burns the legs which correspond to one' hands and feet (with which he performs his actions), and he throws the animal's blood, in lieu of his own soul ("ki ha'Dam Hu ha'Nefesh"), a sign that it is really his blood that ought to go on the Mizbe'ach and his body that ought to be burned, and the limbs of the animal instead of his own limbs - and Hashem in His Mercy, accepts that of his Korban in his place. Whilst parts of the Korban are given to the Kohanim 2 to sustain them so that they should pray on his behalf. 3
The Egyptians, the lamb, the Babylonians, the goat (in the form of demons which resemble a goat), and the Indians, the cow. By bringing these three animals as Korbanos we counter the nations' belief in them, by strengthening our own belief in Hashem (See Ramban, who elaborates in the name of the Rambam, but who rejects his explanation since, such a negative reason would make the Table of Hashem disgusting - and for a number of other reasons).
Those who teach the people Torah (Ramban).
The Ramban's explanation adequately explains the Chatas, the Asham and the Olah, which all come to atone for one's sins; it does not however, explain the Shelamim, Bechor, Ma'aser and Pesach, which are not connected to sin! (EC)
Which water may be used to wash the feet and innards?
Moshav Zekenim: It can be any water, whether flowing or gathered. However, one may not use Mei Kiyor (from the laver), for it has an accompanying name (it is not called plain water), nor with wine mixed with twice its volume of water (for it is called mixed wine).
מכאן דרשו שפרעה נענש ראשון במכות כי הוא פתח בעצת השיעבוד, וקשה למה דוקא פרעה פתח בעצה זו?
מהר"ל (גבורות ה' תחילת פי"ד, עמ' סט): ה' נתן אותם עבדים למלך ולא עבדים לעבדים.