im not sure exactly what happens i get my chapters mixed up, but i think depending on which part of the manga your at if its after the vampire ball kaname gives it back to yuuki, if it is when yuuki and kaname go to the kuran house, kaname keeps it, if its when zero gets his power, kaname gets from yuuki im not sure exactly how but one moment yuuki's best friend gives it to her and the next kaname has it. hope i helped! :)
kaname " DRINKS" yuukis blood in "The Thorny Kiss"when he awakens the vampire in her when her fangs were destroying her from the inside
yes
As of right now no, but he could later on in the series. It looks like he will if Yuuki ever chooses Zero over him.
If you're asking about the anime series Vampire Knight,then Yuki ends up with Kuran Kaname.However, that's the anime. The anime stops after season 2, when Rido is defeated; however, they discontinued the anime. The MANGA is still in progress, and we don't know if Yuuki leaves Kaname for Zero or not, which is a possibility, because she does love him. The cynic in me says that it's unbelievably unlikely for her to choose Zero over Kaname (despite the fact that she and Zero are better suited for each other - Kaname is the easier choice, which is why, I believe, she goes with him in the first place), unless Kaname dies, which I think is also very probable. Typically, the human brain is all about self-preservation - it will go with what's easiest, to prevent being hurt, even if it's futile. It will ignore the heart, and choose the easier solution, rather than the harder one, no matter how wonderful the ending of the harder solution may seem. This is assuming that the author is going for realism, of course.