Probing the flavor-changing tc vertex via tree-level processes: e(+)e(-)->t(c)over-bar-v(e)(v)over-bar-(e), t(c)over-bar-e(+)e(-), and t->cW(+)W(-)

The reaction e(+)e(-) --> <t(c)over bar nu>(e)<(nu)over bar>(e), t(c) over bare$(+)e(-) are very sensitive probes of the flavor-changing-scalar couplings which can occur in a model with one extra Higgs doublet. At the Next Linear Collider, several hundreds and up to thousands of such events may be produced if the mass of the light neutral Higgs is a few hundred GeV. We also briefly comment on the decays t --> cW(+)W(-), t --> cZZ. All of these reactions are severely suppressed in the standard model.