  By combining potential models and QCD spectral sum rules (QSSR), we discuss
the spectroscopy of the $(b\bar c)$ mesons and of the $(bcq)$, $(ccq)$ and
$(bbq)$ baryons (${q}\equiv {d}$ or $s$), the decay constant and the
(semi)leptonic decay modes of the $B_c$ meson. For the masses, the best
predictions come from potential models and read: $M_{B_c} = (6255 \pm 20)$~MeV,
$M_{B^*_c} = (6330 \pm 20)$~MeV, $M_{\Lambda(bcu)} = (6.93\pm 0.05)$~GeV,
$M_{\Omega(bcs)} = (7.00\pm 0.05)$~GeV, $M_{\Xi^*(ccu)} =(3.63\pm 0.05)$~GeV
and $M_{\Xi^*(bbu)} = (10.21\pm 0.05)$~GeV. The decay constant $f_{B_c} = (2.94
\pm 0.21) f_\pi $ is well determined from QSSR and leads to: $\Gamma(B_c
\rightarrow \nu_\tau \tau) = (3.0 \pm 0.4)( V_{cb}/0.037 )^2$ $\times 10^{10}$
s$^{-1}$.The uses of the vertex sum rules for the semileptonic decays of the
$B_c$ show that the $t$-dependence of the form factors is much stronger than
predicted by vector meson dominance. It also predicts the almost equal strength
of about 0.30 $\times 10^{10}$ sec$^{-1}$ for the semileptonic rates $B_c$ into
$B_s, B^*_s,\eta_c$ and J/$\psi$. Besides these phenomenological results, we
also show explicitly how the Wilson coefficients of the $\langle\alpha_s
G^2\rangle$ and $\langle G^3\rangle$ gluon condensates already contain the full
heavy quark- ($\langle\bar QQ\rangle$) and mixed- ($\langle\bar QGQ\rangle$)
condensate contributions in the OPE.}
