What are "Chritzei he'Chalav"?
Rashi citing Targum Yonasan: They are cheeses of milk.
Who is "Sar ha'Elef"?
Rashi #1: He is [the judge] appointed over 1000 who was over Yishai's sons (some texts, and Radak - Yishai). Each Shevet had leaders over each 1,000.
Rashi #2: It is Yonason, who had 1,000 men with him (13:2).
What is "Aruvasam"?
Targum Yonasan: It is their salvation and Shalom. Rashi - take (absorb) it in your ears and heart, and tell me. This is like "Arov Avdecha l'Tov" (Tehilim 119:122), i.e. assurance.
Rashi citing Shabbos 56a: Take from them a divorce document and give it to their wives 1 , to separate the Eiruv (Radak - Kidushin) between him and her.
Radak: It is the securities they gave for their expenses. This was customary for soldiers, for coins are not available in war. Yishai gave to David coins to redeem their securities.
Rashi (56a): He does so lest he die in the war, and his wife would fall to Yibum, or she will be unable to remarry if no one can testify about his death, or if he will be captured.
