1)
What constituted the western border of Reuven and Gad?
2)
What are the connotations of "Ashdos ha'Pisgah?
1.
Rashi and Targum Onkelos and Targum Yonasan: It means below the pouring of the water from the high places 1 (the rapids of the cliff - Artscroll).
1
Refer to Bamidbar, 21:15:1:1.