It means 'You' but used only if you are familar with that person.
This is not Chinese, this is Japanese. I suggest trying freedict.com to find out the answer.
it means "liar".
i think you miss heard this one, it was probably:- "watashi kimi no sei de shinimasu" which is bad news for you because it means "my death will be your fault" i'd leave that one alone mate
It's informal way of saying 'You're cute.'.