Answer:
3. He wanted to play his guitar.
4. Because it was for the day of the dead. To keep the memory of them alive.
5. He taught himself by watch Ernesto De la Cruz play and mimicking his movements.
6. They wanted him to start working in the families shoe shop.
7. Because she was not able to pass to the other side.
8. He went into Ernesto De La Cruz's memorial and stole his guitar.
9. He went to the other side but still in his human form.
10. They are mythical creatures that guide the dead.
Explanation: I watched it many times with my family and it's just a very memorable movie :)