Yep, they are rare, but there are binary star systems in the universe. I had one in EE pre-wipe; it was nice except for when that second sun liked to sucker punch me on the way to my base. Each star in a binary has its own try-to-kill-you radius.
Depends on the angle you look at the block. I noticed that looking up at blocks looks like the picture in the OP, but looking DOWN doesn't. Here's an example:God yes. As someone that works with a lot of standard black armor, its a NIGHTMARE.
You can't see squat. Just outline the edges in white like they were build helper blocks or something, anything!