Which Mizbe'ach is the Pasuk referring to?
Rashi: It is referring to the Mizbe'ach ha'Ketores which stood before Hashem in the Heichal.
Where did he go out to?
Rashi: After standing between the Paroches and the Mizbe'ach (in order to sprinkle towards the Paroches), he moved out to a spot on the far side of the Mizbe'ach in order to sprinkle on the Mizbe'ach, beginning with the north-eastern corner.
How did he atone for the Mizbe'ach ha'Zahav?