1)
Why does it say "Yaskil Avdi"?
1.
Rashi: In the end of days, My servant Yakov will succeed, i.e. Tzadikim in Yakov.
2.
Radak: This Parashah discusses Galus Yisrael. He is called Avdi, like "va'Atah Yisrael Avdi Yakov Asher Becharticha" (Tehilim 41:8). Yaskil is to succeed, like "va'Yhi David b'Chol Derachav Maskil" (Shmuel I, 18:14). Also Yonason translates so.
3.
Radak (53:12, citing Targum Yonasan): Mashi'ach will succeed.
2)
How will Yakov be very elevated?
1.
Radak: This will be when he succeeds. Every expression of elevation is used, for his level will be very high.