1)
"And they returned to the Land of the Pelishtim"? But weren't they already in the Land of Pelishtim?
1.
Ramban: The Pasuk means that they returned to their home-town in Pelishtim - Gerar; whereas Avraham lived in Be'er Sheva, which was situated in the valley of Gerar (also in the territory of the Pelishtim).
2.
Seforno: No! Avimelech and Pichol went to visit Avraham in Be'er Sheva, where he had gone to tend to his sheep, in order to make a covenant with him - and Be'er Sheva is not in the Land of Pelishtim.
