  We present a transfer matrix approach that combines the
Blonder-Tinkham-Klapwijk (BTK) formalism and self-consistent solutions to the
Bogolibuov-de Gennes (BdG) equations and use it to study the tunneling
conductance and spin transport in ferromagnet (${\rm F}$)-superconductor (${\rm
S}$) trilayers (${\rm F_1F_2 S}$) as functions of bias voltage. The
self-consistency ensures that the spin and charge conservation laws are
properly satisfied. We consider forward and angularly averaged conductances
over a broad range of the strength of the exchange fields and ${\rm F}$
thicknesses, as the relative in-plane magnetization angle, $\phi$, between the
two ferromagnets varies. The $\phi$-dependence of the self-consistent
conductance curves in the trilayers can differ substantially from that obtained
via a non-self-consistent approach. The zero bias forward conductance peak
exhibits, as $\phi$ varies, resonance effects intricately associated with
particular combinations of the geometrical and material parameters. We find,
when the magnetizations are non-collinear, signatures of the anomalous Andreev
reflections in the subgap regions of the angularly averaged conductances. When
${\rm F_1}$ is half-metallic, the angularly averaged subgap conductance chiefly
arises from anomalous Andreev reflection. The in-plane components of the spin
current are strongly bias dependent, while the out-of-plane spin current
component is only weakly dependent upon voltage. The components of the spin
current aligned with the local exchange field of one of the F layers are
conserved in that layer and in the S region, while they oscillate in the other
layer. We compute the spin transfer torques, in connection with the oscillatory
behavior of spin currents, and verify that the spin continuity equation is
strictly obeyed in our method.
