in a nutshell...

music > harmony {or dissonance if thats what youre into} within sounds > waves and frequency > physics/geometry > math

keys are kind of arbitrary, its really just whatever- I personally prefer the C#, D, and A major scales. why? Ive made so many tracks with that scale so now its just habit

if you really want to you can just use the same key as your favorite songs {so you can mix it in dj sets heheheh}

I personally believe in the theory that different keys give off different moods... likewise with modal scales

heres one link I found if you want to read more on that: http://biteyourownelbow.com/keychar.htm

the wonders of jazz is that you always make a chord progression out of scratch, whether it be your own derived from common root sequences (2-5-1-x), or spicing up the chord progression of a song you want to remix.

as everyone else said 7th chords are an easy way to get a lush jazz sound, theyre probably one of the most prominent, if not the most. feel free to break out of key and walk along the chromatic scale, just do it right (I cant explain what I mean by this, but it just comes with time and experience for what sounds beautifully dissonant, and what just sounds totally totally wrong)

if you want to immerse yourself in basic jazz progression/chords but still want to stay in the electronic music domain, listen to the future club scene (future bass and shit, and no not all of is the Kawaii wannabe wave racer crap if you hate that) bc theyre currently destroying the jazz-electro scene Imo.

also, pop music in the eastern world (jpop/kpop, etc) incorporate tons of jazz in their stuff. I can never find the same old progressions getting old bc theres always a way to make things totally interesting, not like western pop i.e. 1-5-6-4 or pachelbells sequence. why is this so? bc Jazz

cheers

P.S. #PlzDontCopySnailsHouse