What was Moshe's first question ("Who am I ... ?")?
Rashi, Ramban and Seforno and Rashbam: He maintained that he (a simple shepherd) was not worthy to speak with kings. 1
Seforno: He was afraid that Pharaoh would not take his warning seriously.
And that Pharaoh would not take his warning seriously (Seforno). Rashbam - I am not worthy even to bring to him a gift. Moshe felt that if he were to ask Pharaoh to relinquish the entire nation (Refer to 3:10:1:2), he would kill him - just as Shmuel argued when Hashem instructed him to go and anoint David, see Shmuel 1, 16:2 (Ramban)
What was Moshe's second question (" ... that I should take Yisrael out of Egypt?")?
Rashi and Seforno: He claimed that Yisrael were not worthy of miracles, that he should take them out of Egypt 1 .
Ramban: Just as Pharaoh would never listen to him, so too, would Yisrael, who were an intelligent people, not listen to him, to leave Egypt and follow him to a country whose inhabitants were more numerous and more powerful than them. 2
Rashbam, Rosh (verse 3): He argued that, even if he would be worthy to appear before kings, he was ignorant in all other matters, and besides, what could he possibly say to Pharaoh, to convince him to set free an entire nation of slaves with nothing in exchange!? Was Pharaoh crazy?
Moshav Zekenim: Surely Pharaoh will want to kill me, like he wanted to earlier!
And that he would therefore not merit success in taking Yisrael out of Egypt (Seforno).
Ramban: As Hashem had told him in Pasuk 8 Ramban). Moshe was not afraid that they would listen to him to down tools and to go free, or to go three days into the desert to bring sacrifices; why shouldn't they? But to follow him to Eretz Cana'an, that was something else. As a matter of fact, the fear of fighting the Cana'anim plagued them continually, both in Egypt and in the desert.
רש"י: מה זכו ישראל: מנין לפרש כך?
גור אריה: לא כתוב 'מי אני שאוציא' אלא "וכי אוציא", מכאן שזה דבר בפני עצמו.