Why did Moshe add the word "ha'Nosarim"?
Rashi #2 (in Chagigah, 11b): They too, deserved to be burnt, and they were spared only because Hashem took pity on Aharon.
Which Minchah is "ha'Minchah" referring to?
Rashi: It is referring to Minchas Shemini and the Minchah of Nachshon. 1
Why did Moshe see fit to instruct them to eat them?
Rashi (Pasuk 19): Because, although a Kohen Gadol who is an Onein is permitted to bring Korbanos, he is not permitted to eat them.
Seeing as all S'tam Menachos are brought as Matzos, why did he need to add the word "Matzos"?
Rashi: Because this Minchah was unique, inasmuch as it was a one-time Minchas Tzibur.