from sky to heat - literally
I guess this means "from heaven to hell" - I've never heard this expression.

Wouldn’t it be с небА?

Yes)

Alex, the originals have exclamations marks making them appear to be, well, exclamations, but your translations don’t. So what are these? Phrases? Verbs?

I had to check that online because it was the first time I read it. It's sort of slogan for paratroopers.

blimey

So it’s some sort of call before they jump out of a plane?

I don't think so. As I was searching for that, I saw it as a part of lyrics from a poem about paratroopers. Also, some online articles about troopers have it as a caption. I'm not sure whether it could be called a slogan, but it was definitely designed to immediately call paratroopers to mind.

Ah