Misc: What are followers of the Unification Church called?

Questions

Music : "He's So Fine", "One Fine Day" and "A Love So Fine" where hits for what fine group?

Music : "Joy to the World" was a hit in 1971 for what band with three lead vocalists?

Music : Besides "Auld Lang Syne" and "For He's a Jolly Good Fellow", what is the most frequently sung song in English?

Music : Fifties rock "n" roll was revived by what greased hair, T-shirted, TV frequenting group?

Music : Jerry Lee Lewis had Great _____ Of Fire.?