yes

If the physical evidence backs up your claim, no. If it doesn't, it's clear someone is lying and a murder has been committed instead.

No.
If your life is on the line you are obviously going to try defending yourself

Nope. It isn't a crime in law or life.

If you can prove beyond a shadow of a doubt that they attacked you first then no.

No, its a complete defence. However you would need to prove it was reasonable in the circumstances. If someone punches you, and you kill them... that's unreasonable and the defence won't be upheld

Are we giving you free legal advice sis? What did you do?

No

I hope not, I'm not just gonna let myself be killed like that

No and the judge agreed with me.

Its a crime in the UK, self defence in almost any form is a crime in the UK. Personally I don't think it should be as long as you used reasonable force to defend yourself.

No. Either you defend yourself or you die.

No. Self-defense is not a crime.

It will depend of the country.

Usually if you had no choice, other than killing the person that wanted to kill you, this won't be considered a crime, but if someone came to you to hurt and you ended up killing him, now this is a crime. And of course you have to react right after it happened. If someone had a gun at your head to steal something and he steals and then is going to escape, you can't kill or hurt him, you had to do something when he had the gun at your head.

If you could have reasonably gotten out of the situation without killing them then yes

No, it's not in my opinion.