Correct!
Clue #1: Bad Company - Dave Colwell, who wrote Reach Out, the B-side to WY, was the guitarist of Bad Company at one time.
Clue #2: Melvin - Adrian Smith's early 80's drunken alter ego, similar to Martin Birch's Marvin. Those 2 verses of WY are speaking about that:
But now it seems, I'm just a stranger to myself
And all the things I sometimes do, it isn't me but someone else
And H wrote that.
Clue #3: Thin White Duke - One of David Bowie's characters. Wasted Years was originally named Golden Years, but it was renamed, because of David Bowie's song Golden Years.
Clue #4: Only one person is credited for writing this song - Pretty self explanatory.
Wrong guesses: I'm a Mover, Wrathchild, Stranger In A Strange Land, Holy Smoke, The Assasin, Prodigal Son, The Man Who Would Be King, If Eternity Should Fail, Rime Of The Acient Mariner
Again, can I ask you, how did you get it?