and using semitone shifts in a manner to have a "floating tonality" which Wagner used late on and I think ultimately led to the breakdown of the tonal system, historically speaking.
Ronde, on Wagner's floating tonality as you term it, how would you say that relates to Catoire's music? His music contained, I believe, much polytonalism, and I much enjoy Catoire's music and unique idiom.
Re tremolandi and affect: I think Liszt is mostly using them to add an orchestral sonority and the affect is probably dependent on context: Nuages Gris - ominous, Liebestod - added colour, for example. Beethoven is using them as a harmonic support and to provide the sensation of forward impetus, imo, in the Pathetique.
Augmented chords are probably more universal in their application, because the ear expects a resolution, thus they are by nature unsettling.