That is a kangaroo court; you can't win because every break is usually less than a $5K loser and they know it is not economically feasible to arbitrate the issue ...
Last I heard all of them were against us and the excuse across the board was "bad underlyer" ...
Someday I want to be able to throw away the trades that did not work out ...
I am not sure; however trading profits, i.e. capital gains are outside the scope of the withholding provisions.
And, as traders, not investors, that is the key ...