Kezr

I had a similar problem some time ago. When I was in a certain area and looking a certain direction I got massive frame rate drops for no appearant reason. I had just started that world, so I simply deleted it and started over. Haven't seen the problem since then. I didn't make a tracker post on it then because I lacked any substantial info on what was causing it.
I hope you manage to find a solution sicne deleting an established world is no fun.

The overheating is probably from the Advanced Solar Panel. It is bugged and should be avoided untill it is fixed.
 
Your other problem is a bit odd. I have never played with keep inventory, but try to do the same thing again, that is die while wearing power armor and see if it goes bonkers again. If so, congratulations, you've found a bug, and you should post about it in the tracker as that is where bugs should go.
 
To reset the color, simply go into the coloring GUI and change it back to white. As far as I know there's no other way to do it.

Did you know you can save electromagnets on your fusion reactor by building it against bedrock?