Why does the Torah need to specifically prohibit the blood of Pesulei ha'Mukdashin?
Rashi and Ramban #1 (on Pasuk 22): To teach us that the blood of Pesulei ha'Mukdashin is forbidden, even though it is not sprinkled on the Mizbe'ach. 1
Ramban #2 (on Pasuk 22): In order to exempt it from Kisuy ha'Dam - even though it is compared to Tzvi ve'Ayal. 2
Ramban #3 (on Pasuk 22): Because we would otherwise have thought that, since, once they enter Eretz Yisrael, the blood of Chulin sheep and cattle will be spilt on the ground and not covered, it would be preferable 3 to drink it separately or together with the Basar 4 - even via Nechirah (tearing the Simanim), to prevent people from offering it to demons. 5
Ramban #4 (22, citing the Sifri): The Torah finds it necessary to issue multiple warnings against drinking blood because they were addicted to it. 6
Hadar Zekenim: Because we might otherwise have thought that, just as Pidyon permits the meat to be eaten, it also permits the blood. Therefore the Torah teaches us that it remains Asur. 7
Ramban: Despite the fact that the Torah, in Vayikra, 17:11, specifically connects the Isur of blood to the fact that it is brought on the Mizbe'ach (See Ramban). See also Sifsei Chachamim.
See Ramban as to why this was not applicable in the desert, nor to the blood of deer, gazelle and birds.
Ramban: The Torah repeats this warning later, 15:23, in connection with a B'chor Ba'al-Mum (Pesulei ha'Mukdashin), whose blood was initially destined to go on the Mizbe'ach
Refer to Vayikra, 17:7:4:2.
Ramban: Which explains why the Torah mentions the Isur of blood here a number of times, but not the Isur of Cheilev - even once. Refer to 12:23:1:1**. The Ramban adds that in Egypt, Yisrael became addited to sacrificing to demons - part of the Avodah of which was to drink blood. It seems that this is like Ben Azai who holds that people detest blood (Makos 23b; refer to 12:12:1:2), and they would otherwise not drink
What are the connotations of the phrase "Al ha'Aretz Tishpechenu ka'Mayim"?
Rashi #1 and Ramban: It teaches us that Pesulei ha'Mukdashin are not subject 1 to Kisuy ha'Dam. 2
Rashi #2: It teaches us that it is compared to water and therefore Machshir food to adopt Tum'as Ochlin. 3
Pesachim, 22a: It teaches us thar blood, like water, is Mutar be'Hana'ah (even the blood of the Pesulei ha'Mukdashin - in spite of the fact that the shearings and working with the animal are prohibitted - Pesachim, 22a). 4
Why does the Torah not require covering the blood of sheep and cattle, like it does that of wild animals and fowl?
Ramban: One normally hunts wild animals and fowl in the fields and forests and slaughters them there, 1 so it is necessary to cover the blood to prevent them from being offered to demons who reside there; whereas flock and cattle are slaughtered on one's property (where demons are not commonly found).
Ramban: Before transporting them into town.
