What is the meaning of "va'Yashchinu"?
Rashi citing Zevachim 112b: They built a stone building with curtains on top. 1
When was this?
Radak citing Zevachim 118b: It was after the 14 years of conquest and division.
What is the meaning of "veha'Aretz Nichbeshah Lifneihem"?
Rashi: Once the Mishkan was fixed in place, it was easy to conquer the land.
Bi'ur ha'Gra: The majority of the land was conquered. After Yehoshua died, they conquered the rest.
It was in the southern half of Eretz Yisrael, but presumably it was closer to the middle than to the southern border. Bnei Yosef's portion was north of Binyamin, and a strip from Yosef came to Shilo (it was on the border between Yosef and Binyamin)! Aderes Eliyahu (16:1) - from Yosef and to the north is called Galil; it is the north. Shechem, in Yosef, was in the middle of Eretz Yisrael from south to north, and Chevron, in Yehudah (south of Binyamin) was midway between Shechem and the southern border (Makos 10a).
Also parts of Yehudah in the south were not conquered, e.g. the Yevusi near Yerushalayim (15:63)! This requires investigation. (PF)