  The squark mass-matrix from the soft supersymmetry (SUSY) breaking sector
contains a rich flavor-mixing structure that allows O(1) mixings among top- and
charm-squarks while being consistent with all the existing theoretical and
experimental bounds. We formulate a {\it minimal} flavor-changing-neutral
current scheme in which the squark mixings arise from the non-diagonal scalar
trilinear interactions. This feature can be realized in a class of new models
with horizontal U(1)_H symmetry which generates realistic quark-mass matrices
and provides a solution to the SUSY \mu-problem. Finally, without using the
mass-insertion approximation, we analyze SUSY radiative corrections to the
bcH^+ and tch^0 couplings, and show that these couplings can reveal exciting
new discovery channels for the Higgs boson signals at the Tevatron and the LHC.
