What is the Torah referring to when it writes "ha'Aretz asher Hikah Hashem lifnei Adas Yisrael"?
Rashi: It is referring to the land of Sichon and Og. 1
See Sifsei Chachamim and Oznayim la'Torah DH 'ha'Aretz'.
How could they say "Al T'avirenu es ha'Yarden"? Why did it not occur to them that it would not be fair to avoid fighting the Cana'anim together with the other tribes, as Moshe pointed out to them?
Oznayim la'Torah: They figured that, when Yisrael crossed the Yarden, some troops would anyway need to remain in Eiver ha'Yarden, in order to defend their new territory, and it would make good sense for them to be the ones to do so.
What prompted the B'nei Gad and Reuven to ask to inherit the land of Sichon and Og now and not earlier?
Oznayim la'Torah: When they saw that Yisrael did not take possession of Midyan, it dawned on them that they had taken over the land of Sichon and Og in order to inherit it together with the rest of Eretz Cana'an.
Why does the Torah insert the (otherwise superfluous) words "ve'la'Avadecha Mikneh"?
Tosfos ha'Shalem (in Va'eira Sh'mos, 8:5:1): To teach us the importance of Tefilah - since the same word "ve'la'Avadecha" (plural) appears in two other places 1. in Va'eira, Ibid. - in connection with the plague of frogs; 1 2. in Yirmiyah, 37:18.
Because it explains why the B'nei Reuven and Gad wanted to remain in Eiver ha'Yarden - because the location suited their needs.
Where the Torah goes on to record how Moshe Davened for the frogs to be removed.
