Chakra handouts also replenish his reserves. Just because he used his own chakra, doesn't mean said chakra wasn't replenished several times. He was also healed once or twice by naruto.
What lol? Warp Kamui with Kamui? I'll just assume you mean Amaterasu.
No, he can't. Amaterasu isn't a projectile that he'll be able to intercept with Kamui. It spawns directly on the target of Itachi's gaze.
He might choose not to, and that would be wise, but still somewhat debilitating in battle. It'll also leave him vulnerable to Amaterasu as he won't be able to see the chakra building up in Itachi's eyes, since he's not looking at them.
Also, I don't think Kakashi can resist Tsukuyomi. First of all, Itachi himself said you need to have a true Uchiha bloodline in order to resist it (and we know that much won't be enough on its own because he used Tsukuyomi on Uchiha clansmen with their Sharingan active). So that leads me to believe that you need both the bloodline and an MS in order to resist it. Kakashi doesn't have his MS active all the time anyway, and mostly fights with his regular Sharingan.
Also, Tsukuyomi is so powerful and potent that it was said to be superior to even MS Sasuke's genjutsu by Danzo. (He might've been referring to his regular genjutsu, I don't remember exactly tbh)
He can't. He explicitly can't Kamui very large targets (without Kurama's amp, anyway)
Fair, but at that point there won't be much he can really do about it.