  We perform a series of comparisons between distance-independent photometric
and spectroscopic properties used in the surface brightness fluctuations (SBF)
and fundamental plane (FP) methods of early-type galaxy distance estimation.
The data are taken from two recent surveys: the SBF Survey of Galaxy Distances
and the Streaming Motions of Abell Clusters (SMAC) FP survey. We derive a
relation between V-I colour and Mg_2 index using nearly 200 galaxies and
discuss implications for Galactic extinction estimates and early-type galaxy
stellar populations. We find that the reddenings from Schlegel et al (1998) for
galaxies with $E(B{-}V) \gta 0.2$ mag appear to be overestimated by 5--10%, but
we do not find significant evidence for large-scale dipole errors in the
extinction map. In comparison to stellar population models having solar
elemental abundance ratios, the galaxies in our sample are generally too blue
at a given Mg_2; we ascribe this to the well-known enhancement of the
$\alpha$-elements in luminous early-type galaxies. We confirm a tight relation
between stellar velocity dispersion $\sigma$ and the SBF `fluctuation count'
parameter \Nbar, which is a luminosity-weighted measure of the total number of
stars in a galaxy. The correlation between \Nbar and $\sigma$ is even tighter
than that between Mg_2 and $\sigma$. Finally, we derive FP photometric
parameters for 280 galaxies from the SBF survey data set. Comparisons with
external sources allow us to estimate the errors on these parameters and derive
the correction necessary to bring them onto the SMAC system. The data are used
in a companion paper which compares the distances derived from the FP and SBF
methods.
