To whom does "u'Vanav" refer?
Targum Yonasan: It refers to Moshe's children, as mentioned in the following Pesukim.
Mechilta: It refers to Yisro's children, who came with Yisro to convert. 1
Even though the term "v'Ishto" certainly relates to Moshe.
Why does the Torah see fit to mention the fact that Yisrael were in the desert?
Rashi: In praise of Yisro, who was living comfortably at home, yet he undertook to travel out to the desert in order to hear words of Torah.
Why does the Torah refer to Har Sinai as "Har ha'Elokim," even though Hashem had not yet appeared on it?
Targum Yonasan: Because Hashem already appeared to Moshe upon it, at the episode of the burning bush.
Why must it say "u'Vanav"? It already said "Shnei Vanehah" (18:3)!