Why does the Torah mention specifically the "two lambs of the Shelamim"?
Rashi #1 (on Pasuk 20): To preclude the bull and the rams from the Tenufah 1 (which is performed whilst the lambs are still alive). 2
Rashi #2 (in Pesachim, 13b): Because the Heter to eat the Sh'tei ha'Lechem is dependent upon the two lambs - which are waved together with it - and not upon the other Korbanos mentioned in the previous Pasuk.
Why does the Torah insert the word "le'Zevach Shelamim"?
Sifra: To teach us that they must be Shechted for ths sake of a Shelamim.
How do we know that the Korbanos listed here are not synonymous with the Korban Musaf which the Torah discusses in Pinchas Bamidbar, 28:27?