A few questions about the Twilight Princess Plot

I started playing TP again to show it to my girlfriend, but I came along a few things, that I never really understood in the game.

• After finding the third fused shadow, Zant attacks Link & Midna. What exactly hurts Midna so bad that she is close to death? It seems like the Light Spirit actually hurt her? My understanding is that the light spirit used magic to teleport Link & Midna away to safety, but because of his presence he hurt Midna badly because she is a shadow creature?

• When Zelda "sacrifices" herself to heal Midna, what exactly hapens to her? She just kinda vanishes and we find her at the end of the game being imprisoned by Ganondorf. So did Ganon just actually find her because she used magic to heal Midna or what?

• After defeating Ganon, Midna teleports Link & Zelda away to safety and uses the fused shadows to fight Ganon. It is then implied that she is dead after Ganondorf crunches the fused Shadows. Soo... why is she suddenly still alive at the end? Is there more information on this?

These things always stood out to me as kinda odd and I thought I'd ask about them here to get a second opinion or maybe even links to official sources?

Thanks for taking your time to read all this here!