What is "Eileh ha'Chukim v'ha'Mishpatim ... " referring to?
Seforno: It is referring to all the Mitzvos that are listed before Parshas Bechukosai. 1
Seforno: On which Hashem made a Bris incorporating the Berachos and the Kelalos in Bechukosai. And this is the Bris that the Pasuk refers to in Devarim 28:69. It does not include the forthcoming Mitzvos which the Torah discusses in the following chapter. They were also said at Har Sinai, as the Pasuk testifies at the end of the chapter, but not as part of the covenant.
Why does the Pasuk write "Toros" in the plural?
Rashi: Because it is referring to both Torah shebi'Chsav and Torah she'Ba'al Peh. 1
Rashi: To teach us that the oral Torah too, was given to Moshe at Har Sinai.
What are the implications of the phrase "Beino u'Vein b'nei Yisrael"?
Seforno: It implies that Hashem undertook to bless Yisrael if they keep the Mitzvos, and Yisrael accepted upon themselves the Kelalos in the event that they don't.
Why does the Pasuk insert the words "b'Har Sinai b'Yad Moshe" here?
Rashbam: The Torah is reiterating what it wrote at the beginning of Behar "Vayedaber Hashem el Moshe b'Har Sinai", because the Parshiyos of Behar and Bechukosai both pertain to Shemitah and Yovel. 1
Rashbam: The Pesukim of Behar concern Shemitah and Yovel, sending away Avadim and returning fields. Whereas the curses in Bechukosai are the result of the contravention of the Shemitos and Yovlos, as the Torah wrote earlier (Pasuk 35) "Kol Yemei Hashamah Tishbos".