1)
What are "Gedudim"?
1.
Rashi: When 100 or 200 soldiers go by themselves to plunder what they will find, this is called Gedudim.
2)
Why does it say "Na'arah Ketanah"?
1.
Rashi (from Chulin 5a): She was a minor from a place called Na'aron.
2.
Radak: There is a Na'arah Gedolah 1 ; she was a minor.
1
The first six months of adulthood, i.e. after bringing two hairs after 12 years. (PF)
3)
What is the meaning of "va'Tehi Lifnei"?
1.
Rashi citing Targum Yonasan: She served [Na'aman's wife].