37, 39 I take the ya as interjectional.
39 ame-shiru, heaven-rule.
40 I take the no as connecting 37-40 with midzu in 41. The text is not easy, and the Kogi seems to me rather to shirk the main difficulties.
3 are-tsugu = arahare-tsugu, be manifest, i.e. follow in succession.
For yasumishishi, takahikaru, arataheno, ameshiruya see List m. k.
[Nara no miya ni amenoshita shiroshimeshishi Sumera mikoto no mi-yo.]
15
[Aru hon] Fujihara no miyako yori Nara no miya ni utsurimaseru toki no uta.
Ohokimi no 1
mikoto kashikomi