1)
What is the meaning of "Hashem was with Yehoshua"?
1.
Malbim: The Beis Din above agreed to his Cherem (Yerushalmi Brachos 9:5), and so occurred to Chi'el (who rebuilt Yericho)
2)
What is Sham'o?
1.
Radak: The Nifrad (the word itself, without the suffix) is [a noun] Shoma, like the structure of [the noun] Orach.