1/ you should make Discord send him to the future by accident because he sneezed.... Discord would have brought you back only he didn't know how he sent you forward in the first place...
2/ I'm sure he is trained to have non-lethal take downs for something pony sized, your supposed to use the blade to protect lives, not take them. Ofc you run into a Hydra or an Elder Dragon i'm pretty sure you can kill them and not lose on moral ground if said beasty was gonna eat you.
3/ considering how independant at a young age ponies can be, this one might not be necessary.
4/ Chaos isn't Evil. It is neither good nor bad and do both wonderful thins and terrible things (like discord himself). Dark Magic like Sombra's corruption, Chyrisallis parasitism is. Chaos didn't make Luna into Nightmare Moon after all.
5/You can have fun here. My own OC has a form of nature magic that lets him grow a horn of wood, it basically allows earth ponies to use geomancy but only if he is within the Everfree or another source of nature energy. It sounds harmless when all he can do is grow trees and move the soil... but then he starts growing impaling spine trees and crushing you with the ground