How were Yisrael shown that Hashem alone is Elokim?
Rashi: When Hashem gave Yisrael the Torah, He opened the seven Heavens and they saw that He was alone (that there were no other beings there beside Him). 1
Seforno, Hadar Zekenim and Targum Yonasan: It refers to the signs and miracles mentioned in the previous Pasuk. 2
What are the implications of the statement "Ein Od mi'Levado"?
Rosh Hashanah, 32b: It implies Malchus - as does "Ein Od in Pasuk 39 - and may be recited together with the Pesukim of Malchiyos in Musaf.
Sanedrin, 67b: It implies that nothing can take place without Hashem's authorisation - even via witchcraft.
What are the ramifications of knowing that Hashem is Elokim?
Seforno: To contemplate that Hashem always existed, and His existence is inevitable.
Hadar Zekenim: To realize that one cannot escape Him. He can kill and He can bring to life. Consequently, 'Gguard His Chukim and Mishpatim, since He can benefit you and your descendants, and lengthen your days'.
Why does the Torah say here and elsewhere "Hashem Hu ha'Elokim", and it never says "ha'Elokim Hu Hashem"?
R. Bachye: There are open miracles (associated with the name Hashem) and hidden miracles (amidst nature, which is associated with the name Elokim whose Gematriya is eighty-six, like 'ha'Teva'). The hidden are included in the open. One with intellect will understand this. 2
Because the Name "Hashem" whose acronym is 'Hayah, Hoveh ve'Yih'yeh' denotes the Creator (who is unfathomable), whereas the Name "Elokim", denotes the G-d who communicates with us. 3