Also I your mentioned never having heard of a 7 5 3 triad.  When you build chords you can use 1-3-5-7-9-11-13.  1-3-5 is the basic major or minor triad.  Going to 7 & beyond is an extended harmony chord.  You don't have to use them all, but they are there if you want to use them.  That's how you get dominant 7th chords: 1-3-5-7. And dominant 9th: 1-3-5-7-9.  All chords are built from scale degrees.

Also, you asked "Are all those notes in the scale or should I only be concerned about the chords?"

The answer is both!  You should look at the notes of scale being used to build chords.  That's literally what a key signature is:  a system of chords built on every note of a scale using only notes from that scale.  Check out my tutorials on harmonizing major & minor scales!