This happens a lot. I'll be close to winning a fight and throw a long range spell. The kill cam starts and actually changes the direction of my spell, so that it hits sinto a wall or something. It will do this over and over no matter how much i manually adjust. And, as if it were some kind of mean joke, the attack that actually lands the killing blow does not activate the kill cam.

How can I stop... all of that? Because I really don't like to run out of magicka because the kill cam decides it doesnt want me to win.

Have you tried https://www.nexusmods.com/skyrim/mods/18938/?tab=1&navtag=https%3A%2F%2Fwww.nexusmods.com%2Fskyrim%2Fajax%2Fmoddescription%2F%3Fid%3D18938%26preview%3D&pUp=1?

I disabled my kill cams in general (aside from turning NPCs into a raging cheaters with a very high difficulty set up when we're at melee killcams, they also look ridiculous), but I would've kept ranged killcams if not for that. Missile spells would shoot off, inferno spells would get you stuck in killcam, leaving you vulnerable for a few seconds and svcking your magicka, even though that rabbit is well out of your range for the past half an hour, and the most annoying of all, I actually saw my arrows blatantly going THROUGH an enemy, and not even because he's far away, it would happen even with point blank attacks. The whole feature is just too broken.

I recommend the mod https://www.nexusmods.com/skyrim/mods/56980/?. You're able to control or disable more than just ranged kill cams.