When was the anointing performed?
Ramban #1 (citing Ibn Ezra): It must have taken place before Moshe placed the Mitznefes on Aharon's head, because once the Mitznefes was in place, how could he pour oil on his head? 1
Ramban #2: It took place after the Mitznefes was in place. 2
How was the anointing performed?
Ramban: The turban was wound round the outside of Aharon's head, and Moshe poured the oil in the space on top.
Why does the Torah not include Aharon's sons in the anointing, seeing as they too were anointed, as we saw in 28:41 and in Pikudei, 40:15?
See Oznayim la'Torah, who discusses the matter but does not arrive at a satisfactory conclusion.