God used this rhetorical question to say that he was going to talk to Abraham about something very important and that it was best for him to do so. AT: "I should not and will not hide from Abraham what I am about to do ... him." or "I should and will tell Abraham what I am about to do ... him" (See: [[rc://en/ta/man/translate/figs-rquestion]])
This can be stated in active form. AT: "I will bless all the nations of the earth through Abraham" (See: [[rc://en/ta/man/translate/figs-activepassive]])
"will be blessed because of Abraham" or "will be blessed because I have blessed Abraham." For translating "in him" see how you translated "through you" in [Genesis 12:3](../12/01.md).
Yahweh is speaking about himself as if he were another person. AT: "to obey what I, Yahweh, require ... I, Yahweh, may bring ... I have said" (See: [[rc://en/ta/man/translate/figs-123person]])