Why is He called "Elokei Yisrael"?
Malbim: When Hashem will gather the dispersed and renew His world, He will always be Elokei Yisrael, overseeing them and bonded in love of them.
Why does it say "Min ha'Olam v'Ad ha'Olam"?
Radak: From this world until the world to come.
Radak: From the first time until the last time - i.e. all days.
Malbim: The name Elokei Yisrael, is blessed from this world, in which He conducts with hidden miracles and covert Hashgachah, until the future world, in which Shem Kodsho will be revealed with open miracles.
To whom do they answer Amen?
Radak: The wise praise Hashem according to their intellect, and the entire nation answers Amen, and they will say to each other Hallelukah.
