One thing I know; he was barely 10!
4
His music and music writing skills
Playing music/writing it, of course!
Mozart wrote it in 1787
Mozart didn't write he composed music. So to answer your question the answer is zero or none.
4 to 5
Around age 4 or 5.
Mozart's father (Leopold Mozart) helped influence his music.
Mozart Composed Classical Music.
Mozart [1756 to 1791] Mozart wrote the Ave Verum in June 1791, six months before he died. He was 35 years of age. Had he lived, one wonders what other beautiful music he would have left us with. Marian Cooper
He is the person who catalogued Mozart's music. Hence Mozart's compositions are identified by K numbers.
At the age of three, it was apparent that Mozart was a musical prodigy and he was taught to play the harpsichord, violin, and organ by his father. More about Mozart can be found at - http://en.wikipedia.org/wiki/Wolfgang_Amadeus_Mozart