Misc: what is the basic unit of currency for sri lanka?

Questions

This woman had the unfortunate luck to sing with Paul Anka on "Having My Baby"?

Those big black cd's that you see at garage sales that people call "albums" are made of _____?

Though they had 9 #1s in the UK, Abba's only #1 was this?

Title & Last Name of Lyricist: "I never had the least notion that I could fall with so much devotion..."?

Title & Last Name of Lyricist: "Shake your thang, like a boomerang..."?