Thou shalt cleanse the altar - The altar was to be sanctified for seven days; and it is likely that on each day, previously to the consecration service, the altar was wiped clean, and the former day's ashes, etc., removed.
The consecration of the priests. See the notes to Exodus 29:4
Door of the tabernacle - Entrance of the tent. See Leviticus 8:3.
The “waving” was the more solemn process of the two: it was a movement several times repeated, while “heaving” was simply a “lifting up” once.
A stranger - One of another family, i. e. in this case, one not of the family of Aaron.