1)
Why does it say that he was shearing his flock?
1.
Rashi: The custom is was to make a feast when doing so. Radak - we find that Naval did so (1:25).
2)
Why does it say "Im Efrayim"?
1.
Radak: This is like near Efrayim. The same applies to "va'Yeshev Yitzchak Im Be'er la'Chai Ro'i" (Bereishis 25:11).
