  We compute several total and differential cross sections relevant to top,
  WWZ and Higgs physics at future $e^+e^-$ colliders taking into account the
full set of Feynman diagrams for six fermion final states. We examine in
particular charged current processes, in which final particles cannot be formed
by three Z's decay. We include in our calculations initial state radiation and
beamstrahlung effects, and the most important QCD corrections in an approximate
(naive) form. We also compare this complete approach with production $\times$
decay approximation.
