Capt Birdseye--it is true that a C11 has the same notes in it as a Csus4, but one of my pet nitpicky points is that technically, a suspended 4th isn't really a chord name, it imeans that an out of chord note is suspended over the chord and resolves to one of the pitches in the chord, usually the 3rd. The C11 is an extended dominant chord, and when fully voiced, includes C E G Bb D F.

As I understand the quartal thing--you would take that C11 chord and break it up into what you might call interior voicings, that is, triads from within the extended chord that are fourths--there are three C-F-Bb, G-C-F, and D-G-C. You'd use patterns of those chords as a substitute for the chord.

You could do that same sort of number on each of the chords in you chord progression and then you'd be able to do all kinds of things--how good they'd sound would depend, of course, but it definitely opens up a lot of possibilities--