Playing Volia

(1) How many people play it?

我猜你是指管弦樂隊有多少人 play violas or …. ?.

There would normally be 12 violas in an orchestra (a few have 10 violas)

(2) who is famous in playing it?Give more detailabout he or she.

Some famous viola players are:
Carl Stamitz (1745-1801) German
Lionel Tertis (1876-1975) English
William Primrose (1904-1982) Scottish
Nobuko Imai 今井 信子(born in 1943) Japanese, also plays violin
Yuri Bashmet (born in 1953) Russian , also plays violin
Lawrence Power (born in 1978) British

個別的人資料, 請參考
http://www.classical-music.com/feature/world-music/six-best-viola-players
題外:Recently I had three of my answers deleted in the classical music section. Please acknowledge you read the messages posted by others and me. Thank you.

2013-04-15 11:49:36 補充：
This is to acknowledge 發問者：匿名's comment.
Thanks a lot!