Misc: who played marcus welby?

Questions

Who paid Scriabin a annual fee for composing and took him on an orchestral tour down the Volga by boat ?

Who became intrigued by mechanical player pianos and wrote an Etude for Pianola ?

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 ?