AM doesn’t reach further than FM, it’s just that historically we’ve been using AM at lower frequencies, and these travel further. You could transmit with FM just as well on these frequencies, and get the same range.
These radio telescopes don’t transmit anything at all, they listen to radio waves coming from the cosmos. Much like a normal telescope doesn’t transmit light.
The fumes are from the flux, if you’re evaporating lead your iron is a few thousand degrees too high.
Still shouldn’t breathe that, but that’s also true for lead-free solder