Which comes first: chords or meloody? That's the chicken and egg question facing any music maker staring at a blank DAW screen, and there's no right answer as to which you need to nail first. And ...
Johnny Cash's Hurt hits way different in A Major, as much so as Ring of Fire in G Minor. The dissonance in tone between the chords is, ahem, a minor one: simply the third note lowered to a flat. But ...