Parsha Questions - Shemot

I think there are still questions coming from someone else, but just to get it going, here's something that caught my eye this year and maybe some of you who are learning / teaching Shemot, or did it in years past can help me out.

When Moshe first encounters the סנה (burning bush) it says וַיֵּרָא מַלְאַךְ יְקֹוָק אֵלָיו בְּלַבַּת אֵשׁ מִתּוֹךְ הַסְּנֶה וַיַּרְא וְהִנֵּה סְּנֶה בֹּעֵר בָּאֵשׁ וְהַסְּנֶה אֵינֶנּוּ אֻכָּל:  The Malach appears to him, he then responds, and then Hashem Himself repies back.  Who or what is this malach?  Was there an angel there, and if so, what did it do?  I can't remember if I saw this anywhere, but I'm inclined to believe that malach over here doesn't mean angel but agent of Hashem, in this case referring to the סנה itself.

In general, it's interesting to keep your eye on who is doing the talking in all instances of prophecy - Hashem or a malach, and why.  Maybe I'll follow up on this one day.