Misc: mice, whales, elephants, giraffes and ---------- all have seven neck vertebra?

Questions

What violinist was said to have sold his soul to the devil ?

Who was known as "twelve tone man" ?

For whom did Berlioz write his viola concerto Harold in Italy ?

What composer became so depressed, he needed hypnotism before he could write again ?

Who achieved fame as an organist and a tester of church organs ?