IMO trying to make execution humane is kinda pointless. It is really just done to ease the guilt of those who participate and watch in it. If you participate in killing someone, you should feel guilty. That applies equally no matter if your carrying out a state-sanctioned murder or a street murder.
Uh ... Yes. Everyone has an innate survival instinct. Sure in what seems like a shitty situation, life might feel hopeless temporarily, but I'd bet you'll eventually adapt and get over the initial shock. I'm not sure what you mean by proper, but to me it seems like proper is just shorthand for what is profitable, useful, or easy to people with power.
Well it is better in the cases of actually innocent people getting convicted as it can later be overturned but there are some monsters that really shouldn't be allowed to stain the earth with their existence that we have zero doubt as to their guilt.