Even Parshas Toldos (until the next Shabbos) is connected to [the Shabbos before:] Chayey Sarah. The marriage of Yitzchok and Rivka is the example chosen to demonstrate Hashem’s love for the Avos because it represents the marriage of Hashem and Yidden . The kidushin is achieved through the nose ring (Mitzvos, like machatzis hashekel) and...
The story of this marriage is very important and it was achieved by giving (a nose ring) Mitzvos and (Two bracelets that correspond to the Aseres HaDibros) Torah on the level of Chakika (engraving) Page 184.
Eved means Kabalas Ol, and the Torah in this case is Osiyos Hachakika, so the Bittul is on the level of Chakika. This is why this story is chosen to demonstrate Hashem’s love for ‘avdei batei Avos’. Page 185.
Smicha before the wedding, why? Halacha never changes. like marriage that is forever. Page 185-6.
Smicha before the Chassuna is like a shmira, similar to the idea that Yitzchok was in gan Eden until his Chassuna from the time of the Akaida. Page 186-7, 90.
Shmira from leumas ze outside of Gan Eden. Eretz Yisroel and chutz La’aretz, Nigla and Kabbalah (the Arizal perspired) Shabbos and the weekdays. Shmira for weddings so only good will come into the marriage. Page 188-90.