1)
When was this war?
1.
Rashi: It was before all of these. It is written here merely to put together the death of Orpah's four sons.
2)
In Divrei ha'Yamim I, 20:4, it says that the war was in Gezer!
1.
Radak, Malbim: The place had two names. We find this often in Tanach. Also here it says Saf, and there it says Sipai; these names are close to each other.
