the piano and the violin
No. They both wrote a lot of music for voice. As just two famous examples: Bach's Mass in B Minor, and Handel's "Messiah".
It has a lot to do with music. Music is a way to show emotions like love and hate. Music can remind you of an occasion or someone you love. When you play an instrument, you put your love for playing by music.
The classical era was mostly instrumental. The cantata was used a lot in the baroque era with composer like JS bach and George Handel.
Robin Hood had a minstrel player who played music on the minstrel, similar to the guitar, only a lot older musical instrument.
A lot because robots are basically computers and most computers are used to write music.
If you are asking if you need to know other people's songs, no. But if you are asking if you need to know how to play, it would be helpful! Or, if you don't know how to play an instrument, you can just write lyrics but you'll need someone to do the music.
The Jonas Brother's write there own songs. A lot of them.
A lot of it, but the rest of the band also contributes.
Drums, along with chanting and clapping. Rhythm plays a big role in a lot of traditional African music.
There are a lot of music lessons that are avaialble online. It depends on what type of instrument are you interested in playing. www.gopiano.com/ has the piano lessons and guitar.about.com/library/blguitarlessonarchive.htm has the guitar lessons.
There is a nice website - Load.CD - with a lot of free legal sheet music for any instrument. All epoches are presented - from classical to contemporary composers. Music scores are in pdf format and are available for downloading and printing.
The marimba is the national musical instrument of Costa Rica.