About N°2, I can confirm that sometimes lightining balls target you, start building stacks then switch to another target without any visible reason.
Happened to me as you can see here
on Manalyssaa's twitch. At 01:17:01, the ball at the top right hand corner on the screen starts hitting me. Then, at 01:17:07, it switches to Mana and then 1 second later to Grantz. It followed Grantz til he made it explode. Coincidence or not, all three of us are heals.