Why did he say "Al Mishmarti E'emodah"?
Rashi citing Ta'anis 23a: Chabakuk drew a circle and stood inside, and said 'I will not move from here until I hear what He will speak to me about this question ? why does He see the Rasha's success?
Radak: The Navi said, on this perplexity, I wait to see what Hashem will answer me about the Rasha's success.
Malbim: He stands on the guard and looks forward to Hashem's salvation.
What is the meaning of "v'Esyatzevah Al Matzor"?
Radak: This is like a person who is besieged; he has no escape. So I have no escape from this perplexity ? why does Resha'im's way succeed?
Malbim: Mishmar protects on something guarded, e.g. "v'Shomerei Mishmeres Beis ha'Melech", "Mishmeres ha'Bayis" (Melachim II, 11:5-6). Matzor is to conquer something that he besieges. On Perek 1, Chabakuk prayed to remove the evil from Yisrael, and questioned the success of the evil Bavel. "Al Mishmarti E'emodah" ? to see what Hashem will speak to me about my Tefilah. This is not Vichu'ach, for I know that Yisrael deserve punishment for their evil deeds. "V'Esyatzevah Al Matzor" to see how He will answer my argument about Bavel's success. Here he thought to conquer (win in his argument).
What do we learn from "Mah Yedaber Bi"?
Radak: What He will speak to me with Ru'ach Nevu'ah. This is like "Ru'ach Hashem Diber Bi" (Shmuel II, 23:2).
What is the significance of "[u'Mah Ashiv] Al Tochachti"?
Rashi: What will I answer those who come to argue with me? They argue in front of me that there are gripes against Midas ha'Din. Tochachti is my proof.
Radak: What will I answer those who ask me? Not only I am confused about this!
Malbim: I do not complain to Hashem ? these are complaints of the generation about ways of Hashgachah. How can I answer them?