1)
Why does it say "Al Beiso"?
1.
Radak: This is like El Beiso. Similarly "va'Tispalel Al Hashem" (1:10) is like El Hashem.
2)
Why does it say that he served Hashem, Eli's countenance?
1.
Rashi (citing Eruvin 5:1): This teaches that serving Chachamim is like serving the countenance of the Shechinah.
3)
Why does it say "Es Pnei Eli"?
1.
Radak: This is like Lifnei [Eli]. Eli taught him Avodas Hashem.
2.
Targum Yonasan: In the life of Eli the Kohen. Radak - this is like Targum Onkelos of (Devarim 7:10) "Al Panav Leha'avido" - b'Chayeihon Le'ovdeihon.