1)
Having issued a La'av against working on Yom Kipur in Pasuk 28, why does the Torah repeat it here?
1.
Rashi #1: To add a second La'av. 1
2.
Rashi #2: To include the night of Yom Kipur in the Isur. 2
1
Uoma, 81a: The Torah presents five Pesukim with regard to the prohibition against Melachah on Yom Kipur - See Torah Temmah, note 95 - One, a warning against performing Melachah in the day and one ... in the night (See Torah Temimah, note 96); one, the punishment for performing Melachah in the day, and one ... in the night, and one to learn a Gezeirah Shavah from Melachah on to Inuy.
2
See Sifsei Chachamim.
2)
What are the implications of "be'Chol Moshvoseichem"?
