Why does it say "l'Es Yom b'Yom?"?
'Rashi': This explains why the verses discuss who came to David, to show that they were constantly coming to him.
Malbim: Once David returned to Yehudah, they declared him king, people came from other Shevatim and added to his camp constantly, like it says in Shmuel II, 3:1 "v'David Holech v'Chazak."
Why does it say "k'Machaneh Elokim"?
'Rashi' #1: David's camp should not have been so big. However, it was from Hashem; He caused it to be so big. Also "Machaneh Elokim" (Bereishis 32:2) of Yakov is like this.
'Rashi' #2: Because there were so many soldiers, it was called Machaneh Elokim. Radak ? to show great size, matters are attributed to Hashem, e.g. "k'Harerei Kel" (Tehilim 36:7), "Ir Gedolah lEi'lokim" (Yonah 3:3), "Shalhevesyah" (Shir ha'Shirim 8:6), "Mapelyah" (Yirmeyah 2:21). Even though each of the latter is one word, it is as if each is two words.
Vilna Gaon: Just like Yisrael who left Egypt had officers over 1000 and over 100, also David's camp.
