  Let $(X,g)$ be a compact manifold with boundary $M^n$ and $\sigma$ a defining
function of $M$. To these data, we associate natural conformally covariant
polynomial one-parameter families of differential operators $C^\infty(X) \to
C^\infty(M)$. They arise through a residue construction which generalizes an
earlier construction in the framework of Poincar\'e-Einstein metrics. The main
ingredient of the definition of residue families are eigenfunctions of the
Laplacian of the singular metric $\sigma^{-2}g$. We prove that if $\sigma$ is
an approximate solution of a singular Yamabe problem, these families can be
written as compositions of certain degenerate Laplacians. This result implies
that the notions of extrinsic conformal Laplacians and extrinsic $Q$-curvature
introduced in recent works by Gover and Waldron can naturally be rephrased in
terms of residue families. The new spectral theoretical perspective enables us
to relate the extrinsic conformal Laplacians and the critical extrinsic
$Q$-curvature to the scattering operator of the asymptotically hyperbolic
metric $\sigma^{-2}g$ extending the work of Graham and Zworski. The latter
relation implies that the extrinsic conformal Laplacians are self-adjoint. We
describe the asymptotic expansion of the volume of a singular Yamabe metric in
terms of Laplace-Robin operators. We also derive new local holographic formulas
for all extrinsic $Q$-curvatures in terms of renormalized volume coefficients,
the scalar curvature of the background metric, and the asymptotic expansions of
eigenfunctions of the Laplacian of the singular metric $\sigma^{-2}g$.
Furthermore, we prove a new formula for the singular Yamabe obstruction $B_n$,
and we use the latter formula to derive explicit expressions for the
obstructions in low-order cases (confirming earlier results). Finally, we
relate the obstruction $B_n$ to the supercritical $Q$-curvature $Q_{n+1}$.
