I found a very sad song while studying Russian

I am trying to study Russian, and I know music helps a lot to memorize words, specially Russian, that has such a difficult grammar. Today I came across this song about the Russian-Afghan war, and the lyrics are very very sad.

I do not know how I found it, the song is called "Привет Сестрёнка" (Hello, sister), I do not know who the original author is, but there are some versions of it.

The lyrics start well and slow, like the singer is writing a letter (or reading):

"Привет сестрёнка, моя родная, ну как дела"
Hello sister, my dear, how are you doing?
"Зима дороги домой наверно уж замела?"
Winter is probably sweeping/happening at home?

This part is specially shocking, because as far I have read about, he actually means that rockets/bullets/explosions are falling, at first I thought he meant they were shooting stars, but it is way deeper than that:

"А звезды падают над Кандагаром в лучах зари"
And the stars are falling here in the skies of Kandahar

"Ты только маме, что я в Афгане, не говори!"
Something like "and if mom asks about it, just do not tell her that I am in Afghan", so he is asking her to tell anything, no matter how bad it is, as long as she does not tell her mom, he is at the war
"Сейчас суббота, белье почищу я и черт с войной"
Today is Saturday, to hell with this war, I will clean (the linen?) or wash something, I tried translating and it did not make much sense what he is going to clean, if it is his clothes, or himself. But I understood he is not serving today and he just want to pretend everything is fine.
"Здесь пахнет потом, здесь спят парнишки, был трудный бой"
It smells like sweat in here, the men are sleeping, it was a tough fight
"С дружком Олегом, что он вернется держу пари"
I have bet against Oleg that he will be back (from the fight?). It is particularly impacting because it implies that Oleg himself bet that he himself will not survive the fight, so the war was tough and the morale was low, he was probably trying to improve the mood and make Oleg feel better, but from the tone of his voice, it sounds that not even the singer/writer believes in his own words....
"Своей сестренке, я шлю горячий большой привет"
To my little sister/dear sister (not sure if the reader or another sister) I send my kindest regard/great hello/greetings.
"Скажи, пусть пишет, давно из дома уж писем нет"
Tell me, why has there been no letters written to me, back from home?
Here, I did not understand, I think there is a deeper meaning why he is not getting letters from home. There is another song where, apparently, the same writer is fighting in Chechnya, and he again touches on the point that he is not getting letters back from home, I did not understand why, but I think there is a hidden meaning in here that I did not get.
"А если спросит, о чем пишу я, ну что же соври"
And if they (anyone) asks where I am/what am I doing, just lie and make something up. Again, looks like anything would be less worse than telling he is in the war, he does not care if she makes up something bad about him, as long as they don't know he is fighting.

There seems to be many versions of the song, and the writer seems to have been in many fights and written about them. Overall it was a bit hard to understand as I, from South America, do not know much about Russian war on Afghan. So I had to read many comments and search a bit about it, even discovered about a plane called "black tulip" that seemed to transport the dead or severely injured, discovered the name of a few cities over there, and I have learned a bit about history of that side of the world.

I found the song to study the language, and ended up learning a little bit about history, geography and politics.