Seeing as the Par is burnt in its entirety, from where do we know that the insides, the sinews, the horns and the hoofs were included?
Ramban #1: They are included in the word "ha'Par"
Ramban #2: The four extra "Vavin" in "ve'es ha'Par, ve'es Oro, ve'es Besaro ve'es Pirsho" come to include them. 1
Since when is a Chatas Chitzonah (whose blood is sprinkled on the outer Mizbe'ach) entirely burnt?
Rashi (in Vayikra 9:11): The only cases of a Chatas Chitzonah being entirely burnet are the Eil ha'Milu'im (here) and the calf of Aharon's Chatas on the eighth day of the Milu'im.