Then where exactly did it go? I am looking at the footage now. The lightning just hits him, and down he goes. Lightning redirect doesn't negate the lightning, it just keeps it going. It's also supposed to be a very controlled technique, not something you can do when you are being electrocuted, because you have to conciously keep it moving while it's in your body.
Lightning bending isn't a one hit kill. It obviously can be, if it's struck in the spine, but Zuko managed to get up after being struck straight in the middle of his chest. And Mako himself hit Amon point blank, he survived and was fine after a few minutes. And if he doesn't feel it's justified when the alternative is his brother being killed as well as maybe the Avatar/his ex girlfriend being captured/killed, then...idk, I feel in those situations Mako would go all out. Besides that, you're speculating. There is nothing suggesting that Mako would have anything in particular against killing. People have natural instincts that resist that, but I would have thought Lin would put him though some kind of training for that as a police officer.
And with the way his lightning bending works, it's pretty much just aim and shoot. All he needs for practice is a target board.
Nope. You are literally making this up because there is nothing in the show suggesting that this is possible to do.
You're re-directing the the lightning's energy. If Amon can control the water molecules in his body to control his blood with the sheer force of will he can control the energy trajectory of lightning through his body. It's the same as when Amon CLEARLY RESISTS AND USES HIS BLOOD BENDING to counter his brother's blood bending. He isn't just taking the blood bending and walking through it, he's using his own because it's already been shown and announced he can blood bend without moving.