1)
What do we learn from "Avram Hu Avraham"?
1.
Radak: Avram, Terach's son, is the one whom we know as Avraham. Hashem loved him, and aggrandized his name - He made him Av Hamon Goyim. Malbim - "Asher Bacharta b'Avram? v'Samta Shmo Avraham", to show that he will be Av Hamon Goyim.
2.
Malbim: We must call him Avraham. One who calls him Avram transgresses an Aseh (Berachos 13a)!
