To whom did they say "Kumu Barchu"?
Ibn Ezra: They told Yisrael to bless Him.
Why did they say "Min ha'Olam v'Ad ha'Olam"?
Rashi: From the beginning of the world until its end, [Hashem will be blessed].
Ibn Ezra: For eternity, he is your G-d; there is no other.
What is the significance of blessing "Shem Kevodecha"?
Rashi: Now the Leviyim addressed the Shechinah in their hearts.
Malbim: You Yourself are elevated more than any Berachah or praise. No one fathoms You, or Your influence, to praise You! You are totally hidden, above any Berachah or praise. We can bless only Shem Kevodecha - what You are known via Your honor in Your creation. We can bless this, but not You Yourself.
How is Hashem "Merumam Al Kol Berachah u'Sehilah"?
Rashi #1: All Berachos and praises are His.
Rashi #2: No creation can bless and praise Him according to His grandeur, which is more elevated than the mouth can speak.
Ibn Ezra: He will be elevated after we bless Him.
