What are the connotations of "Begadim Acherim"?
Rashi and Ramban: It means inferior Bigdei Kehunah. 1
Ramban and Moshav Zekenim: Some say that they are Bigdei Chol. 2
Why must the Kohen who removes the ashes from the Mizbe'ach change his clothes?
Rashi: Changing into inferior clothes 1 is not obligatory, but the correct thing to do - in order not to dirty the clothes in which he performs major Avodos, whilst performing a secondary Avodah. 2
Ramban: The Kohanim had two sets of clothing, one better quality (newer?), the other, inferior quality - and it is a Mitzvah when taking out the ashes to change into the latter (for the reason mentioned in answer #1).
Which ashes is the Pasuk referring to?
Rashi: The ashes that were piled on the 'Tapu'ach' (the pile of spent ashes that had been removed from the Ma'arachah to the middle of the Mizbe'ach). 1
When it became excessive (Rashi).
Where does the Kohen take the ashes?
Rashi: Refer to 4:12:2:1.
When is Hotza'as ha'Deshen performed?
Rashi: The Torah did not give a specific time. It is perfomed wenever the Tapu'ach is full. 1
Oznayim la'Torah: In fact, the Hotza'as ha'Deshen is not a Mitzvah and is only perfrmed in order to make room for more ashes to be placed on the Mizbe'ach.
Why does the Torah need to add "el Makom Tahor"?
Rashi: Refer to 4:12:3:1.
