Shoftim - R'vi'i
Kohanim and Leviim could live in any territory in Israel. They could come to Jerusalem to offer their own sacrifices, and they could do the appropriate service on their own behalf. If a kohein does this, he can eat the priestly portions along with the kohanim who are on duty that week.
When the Jews enter Israel, they are not to copy the ways of the Canaanite nations being expelled. Sorcery, witchcraft, fortune telling, etc. are all prohibited - to say nothing of passing one's children through fire! (God really hates that one!) These practices of magic and necromancy are disgusting to God. He drove the Canaanites out because of them, so they are not to be emulated.