Country (or country and western) is a musical genre that originated in the southern United States 
Who is your favorite Country artist?
Don't really have one, Country music often consists of ballads and dance tunes with generally simple forms, folk lyric and harmonies 
Why do most country music singers hire other people to write songs for them?
That is most of their way.  According to Lindsey Starnes, the term "country music" gained popularity in the 1940s