#1
So I've been thinking about the names of the three minor scales - Natural, Harmonic, and Melodic. This may constitute a silly question to some of you but I never actually thought about the names of the scales until now and I haven't seen textbook description to explain it.

Is there a reason for these names and do they apply to specific sound? Throwing Natural out of the equation (because I feel it's neutral to the other two), is it Harmonic minor because there are special harmonic functions and tendencies (besides the need for a raised 7th scale degree)? And is it Melodic minor because there are special melodic functions or melodies you could use within a song?
We're all alright!
#2
Well, the raised 7th in the Harmonic Minor creates stronger harmonic resolution to the tonic (think V7 -> i and vii* -> i), thus 'Harmonic Minor.' However, this left an augmented 2nd gap from the b6 to 7 of said scale. To smooth this over, you raise the b6 to 6 to create a smoother sounding major second interval; this creates a more flowing melodic line, thus 'Melodic Minor.'
Nothing that is worthwhile in life will ever come easy.
#3
harmony is derived from the harmonic minor scale, melody from the melodic minor. or at least it was back in the day!