  We present a detailed characterization of the 849 broad-line quasars from the
Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project. Our quasar
sample covers a redshift range of 0.1<z<4.5 and is flux-limited to i_PSF<21.7
without any other cuts on quasar properties. The main sample characterization
includes: 1) spectral measurements of the continuum and broad emission lines
for individual objects from the coadded first-season spectroscopy in 2014; 2)
identification of broad and narrow absorption lines in the spectra; 3) optical
variability properties for continuum and broad lines from multi-epoch
spectroscopy. We provide improved systemic redshift estimates for all quasars,
and demonstrate the effects of signal-to-noise ratio on the spectral
measurements. We compile measured properties for all 849 quasars along with
supplemental multi-wavelength data for subsets of our sample from other
surveys. The SDSS-RM sample probes a diverse range in quasar properties, and
shows well detected continuum and broad-line variability for many objects from
first-season monitoring data. The compiled properties serve as the benchmark
for follow-up work based on SDSS-RM data. The spectral fitting tools are made
public along with this work.
