What Am I Riddles

Question: You can find them on plants. One is for music. Most have two. Someone may ask you for yours. Politely, you lend yours to another. Only if you are good you can play by it.

Question: Without one or the other both would not exist. what i'm I ?

Question: I am a cold man without a soul. If there is warmth in me, it slowly will kill me. What am I?

Question: What grows when it eats, but dies when it drinks?

Question: When is... 5>0, 0>2 and 2>5? Hint: Hands