Elliott carter's technique of using many precisely regulated changes in the speed of the music in order to give it a feeling of fluidity is known as\

Eliott Carter was an American composer, whose personal harmonic and rhythmic language led to the invention of the term metric modulation. The latter describes frequent, precise tempo changes. In David Schiff's book "The Music of Elliott Carter", it is written that Elliott Carter preferred to call it tempo modulation. 

It depends on what type of third separates the three notes.for example: if you have two mayor thirds is an "aumented chord"if you have two minor thirds is an "diminued chord"if you have one mayor first and then one minor is a "mayor chord"and inverted is a "minor chord"