ThreadJacking: Go right ahead. <3 I love threadjacks.
Mind Reading: His mind is very much "human," possessing free will, free thoughts, memories, and other such things -- however, it is still a robotic mind. Whether or not your character can read his mind is up to you.
Spiritual Sense: Go ahead, if your character can. Just keep in mind that, while X does in fact have a soul, it's far different from human souls.
Hugging: Absolutely! X loves hugs, and will gladly return them.
Kissing: Sure. =D X will be adorably flustered.
Fourth Walling: Ah... why not? Go ahead. Just don't expect a certain reaction.
Hacking: Get ahold of me and ask. I don't think X is "hackable," at least in the normal sense, so I'd rather talk to you about it.
Fighting/Injuring: Go ahead. Please keep in mind that X is hard to actively harm with normal weapons, and that unless you're threatening someone besides him, he likely won't fight back. He doesn't like violence, so he's impossible to bait into fighting normally. The only way to guarantee that X will fight you is to actively (not through words) threaten someone; be aware, though, that while threatening an innocent person will get him angry enough to fight to protect them, threatening one of his friends will actively piss him off.
Disabling: Talk to me first. I'm open to X being disabled if your character is strong enough to damage his body to that point or accurate enough to hit the gem on his helmet. Note that this is not the same as killing.
Killing: I'm going to say no on this one. As Reploids can be brought back as long as their bodies and control chips are intact, killing even an average one for good can be difficult. As X is far from average, and very well equipped, the sheer amount of power and force needed to completely destroy his body is something only very few characters would possess -- and I don't want him to die for good.