I personally am not a brass player but from what I read about brass instruments the notes they play in a certain fingering are dependent on the harmonic series.
However out of all the recordings of such harmonic series being played on brass instruments I have yet to hear one play past the 8th harmonic—so thus I have a few questions to ask those of you that do play brass instruments.

(A) Is it possible for Brass Instruments to play 9th and higher harmonics?
(B) If so, is it actually useful or does after the 8th harmonic the quality of the tone become worse?
(C) Does it require special technique to play 9th and higher harmonics?