  We present an improved analysis of halo substructure traced by RR Lyrae stars
in the SDSS stripe 82 region. With the addition of SDSS-II data, a revised
selection method based on new ugriz light curve templates results in a sample
of 483 RR Lyrae stars that is essentially free of contamination. The main
result from our first study persists: the spatial distribution of halo stars at
galactocentric distances 5--100 kpc is highly inhomogeneous. At least 20% of
halo stars within 30 kpc from the Galactic center can be statistically
associated with substructure. We present strong direct evidence, based on both
RR Lyrae stars and main sequence stars, that the halo stellar number density
profile significantly steepens beyond a Galactocentric distance of ~30 kpc, and
a larger fraction of the stars are associated with substructure. By using a
novel method that simultaneously combines data for RR Lyrae and main sequence
stars, and using photometric metallicity estimates for main sequence stars
derived from deep co-added u-band data, we measure the metallicity of the
Sagittarius dSph tidal stream (trailing arm) towards R.A.2h-3h and Dec~0 deg to
be 0.3 dex higher ([Fe/H]=-1.2) than that of surrounding halo field stars.
Together with a similar result for another major halo substructure, the
Monoceros stream, these results support theoretical predictions that an early
forming, smooth inner halo, is metal poor compared to high surface brightness
material that have been accreted onto a later-forming outer halo. The mean
metallicity of stars in the outer halo that are not associated with detectable
clumps may still be more metal-poor than the bulk of inner-halo stars, as has
been argued from other data sets.
