No, she's not. You can't simultaneously be a human being and something else, you're either human or you're not. Dawn is supernatural being, her memories are fake, she was created as a result of magical tinkering and brainwashing. Buffy's not a human either, since season 7 we know that she's pretty much a demon.
Doyle is half-demon, half-human. Do you deem him 'pretty much a demon'?
Dawn was created by supernatural means, but she was created to be a human; ergo, she is human. Biologically and physically and mentally speaking, she is a human. What other gauge would you use?
Power. The same power that allows her to punch things very hard and see the future in prophetic dreams. It's all a part of the package. It's magic, it's not rational.
Physical strength and Slayer dreams. Established 'part of the package'. Your conjecture is not.
Remember Judge?
"No weapon forged can harm me"
He cannot be killed with forged weapons. Done, it's magic. It's part of the spell that created him or a part of his inherent power, we don't know his origin. Slayers are similar, except it looks like this:
"You cannot kill me unless I want to die."
Done. She cannot be killed because the spell that created the Slayer line says so. You can throw bombs at her and it will not work. It's not rational, it's magic. The Master was the only guy ever that managed to kill The Slayer that wanted to live ( "Giles, I'm 16 years old. I don't want to die." ) and just because he discovered the only way to completely turn off her power, by bringing her into the proximity of the cosmic egg and...it still did not work, thanks to that butt monkey Xander Harris.
Lore.
This is not lore. This is not canon. This is fanwank. Nowhere in canon does it even hint that 'the spell that created the Slayer line says so'.
Did Kendra die because she wanted to?
Why yes, of course. That's why we have judiciary, there are different kinds of fault etc. Geez, look it up. One of Faith's murders was more or less accidental and she was trialed for it as well after all. It's bullshit because she's not a human being and shouldn't be trialed at all but whatever.
Self defense has limits too. Google it.
"A person may use non-deadly force to prevent imminent injury, however a person may not use deadly force unless that person is in reasonable fear of serious injury or death."
Buffy didn't use deadly force. She pushed him aside.
Buffy is more important to them than their personal well-being and safety and the well-being and safety of their loved ones.
Buffy is one of their loved ones. They would risk their own lives for her. Other people's lives? Not unless absolutely necessary or the other people agreed.
Willow would have brought Buffy again, she says so herself, she could not live without her. Magic addiction, Tara's death, almost-Armageddon, all the pain and suffering, it was worth it to her. If that's not an obsession then I don't know what is.
That's Willow's storyline, and it has nothing to do with bearing pain for Buffy. The only 'for Buffy' aspect to it is that the resurrection spell dove her into the even darker magicks. Willow didn't give up Tara for Buffy; that was an unforeseen death. Unless you mean by having Tara around Buffy, Tara's life was in danger--which is kind of true(?), but Tara was Buffy's friend and would risk her own life for Buffy too. Plus, Willow was stopped by Xander's friendship, not Buffy.
No. There's nothing contradictory about those statements. Vampires are garbage, torturing them turns you into the same sort of garbage. It's like with animals, it's OK to kill them to eat their meat, make clothes out of their fur and so on ( yes, I know that not everybody shares that view ) but torturing them is all sorts of wrong. We extend some of our human moral rules onto non-humans. It's very much OK to slay a vampire but torture? Way uncool.
Ah, I see. How about this? They were about to raise The Master. Very, very soon. Buffy did what she needed to do to get the info. Now, I'm not denying that it is a morally grey moment, but no more than S6. (S6 includes the mistreatment of a vamp, this scene is the mistreatment of a vamp, but S6 is an entire season of such mistreatment versus this incident which was out of necessity.)
They're willing to suffer for her. Loose a loved one, loose a body part, go insane - whatever it takes, no regrets. They may question her decisions but in the end they always follow her orders and they're willing to do just about anything for her.
Willow and Xander are basically minions, they simply don't realize it.
They are loyal and loving friends. They risk life and limb for her because they love her and believe in what she does. As for loved ones? Not so much. All their loved ones were willing to fight the good fight alongside Buffy as well--except Anya. But when Anya's death finally came, she had already changed; she was determined to fight alongside them, willing to risk her death.