1)
Seeing as in Devarim 34:4 the Torah lists Kadeish Barne'a as part of Eretz Cana'an, how can Moshe have sent spies from there?
1.
Rashi: There were actually two towns by the name of Kadesh Barne'a, one in Eiver ha'Yarden, the other, in Eretz Cana'an.
2.
Da'as Zekenim and Hadar Zekenim (in 34:4 - citing R. Yossi in Makos 10a): There were two places named Kadesh; One is counted in Yehoshua among the towns [west] of the Yarden, the other, in the desert.