When and where did Hashem stroke Ashur's camp?
Rashi: It is after he returned from fighting Kush and came to Yerushalayim. Rashi (Melachim II, 19:35) - he came to Nov, which is near Yerushalayim.
Radak (Melachim II, 19:35, citing Shir ha'Shirim Rabah 1:12): It was Pesach night.
Radak (Melachim II, 19:35, citing Seder Olam 23): It was after Chizkiyah fell ill, on the third day. That night they sang Shirah - "ha'Shir Yihyeh Lachem k'Leil Hiskadesh Chag" (30:29).
Was his camp only 185,000?
Rashi (citing Seder Olam 23) - all 185,000 were kings with crowns on their heads. Each had at least 2,000 soldiers under him (18:23-24); all of them died. Radak - Divrei ha'Yamim II, 32:21 implies like this - "va'Yachched Kol Gibor Chayil v'Nagid v'Sar b'Machaneh Melech Ashur." It says also "b'Mishmanav Razon" (above, 10:16).
Sanhedrin 95b: His camp had about 2,600,000,000 1 soldiers.
Chidushei Agados Maharal (95b): This refers to their spiritual power. The physical number was what is possible in the physical world.
How were they killed?
Radak (Melachim II, 19:35 citing Sanhedrin 94a): "V'Sachas Kevodo Yekad Yekod ki'Kod Esh" - their Neshamos, which are under their actual Kavod (bodies) were burned, like the death of Nadav and Avihu.
R. Yochanan (Sanhedrin 94a): "V'Sachas Kevodo
