Joshua is old. There is still much land to conquer. How much time has passed between chapter 12 and 13? 5 years?
God and Joshua (I tend to first write Moses when I talk about interaction with God. It's really ingrained in my brain!) discuss the borders of the promised land.
Here is a map of how the land was divided up.
At 14:7 we suddenly go to first person. Is it Caleb speaking? Why does he get the center stage all of a sudden?
15:63 As for the Jebusites the inhabitants of Jerusalem, the children of Judah could not drive them out: but the Jebusites dwell with the children of Judah at Jerusalem unto this day.
16:10 And they drave not out the Canaanites that dwelt in Gezer: but the Canaanites dwell among the Ephraimites unto this day, and serve under tribute.
What the heck? God couldn't drive the Jebusites out of Jerusalem?