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

Questions

Who sang with Kiki Dee on "Don't Go Breaking My Heart"?

Who teamed up with Queen for "Under Pressure"?

Who thought it was fun to stay at the Y.M.C.A.?

Who wrote Simon & Garfunkel's "Bridge Over Troubled Water"?

Whose death gave "Bohemian Rhapsody" a second visit to No. 1?