Let Him Greave

דבר אל אהרן אחיך.  We know that Moshe is Aharon's brother, why does the Torah need to specify that here?  Why is there a gap of a few parshiot between the episode of the death of Nadav and Abihu and the subsequent commandments given only in our parsha?  I heard an insight in the name of Rav Nissin Alpert.  When one is in deep pain, they need to be given time and space to be able to move beyond the shock and grief of the moment.  That is why there cannot be commandments directly following the events of Aharons' sons dying.  It is given אחרי which is after some time had passed.  That is why the Torah says אל אהרן אחיך.  These commandments will touch a chord in Aharon and remind him of what happened to his sons.  Such commandments can't be given over as Moshe the teacher but must be given from Moshe the brother.  They must be given with sensitivity and compassion as to not to cause Aharon too much grief.  

A few other scattered points. 

On Chol Hamoed there are speakers in a local shul.  One of them was Rav Aharom Kahn.  He mentioned that there are only two times throughout the year when incorporated into the text in לשנה הבא בירושלים, on Pesach at the end of the Haggadah and on Yom Kippur at the conclusion of neilah.  Why these two times?  Because are entire experience of the holiday is greatly lacking on these two days.  A Yom Tov of Pesach without the actual korban Pesach and a Yom Kippur without the avodah are two holidays where we feel that the day is very lacking without the Mikdash and the korbanot of the day. 

After the avodat hayom the Torah mebtions the issur melacha and the mitzvah of ענוי and only after that is says (16:30) כי ביום הזה יכפר עליכם...  Seemingly that possuk should be placed in the context of the avodah which enacts the atonement?  The possuk is not placed in part of the avodah for it the avodah is a chiuv on the tzibbur, it is how the nation achieves atonement.  Then the Torah tells us the specific obligation of the day that everyone must keep, the issur melacha and ענוי.  Another obligation on every individual is כי ביום הזה יכפר עליכם, to do teshuva (see Seforno.)  It is only with this teshuva that is 'לפני ה, private between each individual and Hashem that one reaches תטהרו, complete cleansing.