Why does the Torah need to introduce the avodah of Yom Kippur with the death of Nadav and Abihu? The Or Hachaim explains the sin of Nadav and Abihu was as the possuk says בקרבתם לפני ה, they desired to come so close to Hashem that their souls could no longer be contained in the human body. When one experiences the sight of the avodat Yom Kippurim and experiences a spiritual uplifting, they may be so ceased by a desire to come close to Hashem that they want to rush into the kodesh kodashim to come into the holiest place on the holiest day. The Torah cautions אל יבא בכל עת אל הקודש. Such actions, although with good intentions are not favorable as was seen in the incident of Nadav and Abihu. Instead the kedusha of the day must inspire one to lead a life of kedusha (see Likutay Sichos volume 3.)
The Rambam at the end of Ch. 4 of Avodat Yom Kippurim describes how the kohan gadol would make a feast when he returned home after Yom Kippur. Why does the Rambam need to cite this in the Laws of Yom Kippur, is this a law in the avodah itself? The point of the avodah is to bring it into the house. To bring the kedusha of the avodah done on Yom Kippur use it to infuse one's life. This is the completion of the avodah itself (see Likutay Sichos volume 32.)
This idea is the bridge between the parshiot of Vakra until now and the parshiot that follow. Most of the parshiot until Acharei deal will laws of korbanot and the erection of the Mishkan. After the parsha of the avodah on Yom Kippur, the Torah gives parshiot with many commandments which have to do with a person's behavior. It is the switch from the kedusha of the Midhkan and its offerings and to take that and infuse one's daily life.