  (Abridged) This is the second in a series of papers in which we derive
simultaneous constraints on cosmology and X-ray scaling relations using
observations of massive, X-ray flux-selected galaxy clusters. The data set
consists of 238 clusters drawn from the ROSAT All-Sky Survey with 0.1-2.4 keV
luminosities >2.5e44 erg/second, and incorporates extensive follow-up
observations using the Chandra X-ray Observatory. Our analysis accounts
self-consistently for all selection effects, covariances and systematic
uncertainties. Here we describe the reduction of the follow-up X-ray
observations, present results on the cluster scaling relations, and discuss
their implications. Our constraints on the luminosity-mass and temperature-mass
relations, measured within r_500, lead to three important results. First, the
data support the conclusion that excess heating of the intracluster medium has
altered its thermodynamic state from that expected in a simple, gravitationally
dominated system; however, this excess heating is primarily limited to the
central regions of clusters (r<0.15r_500). Second, the intrinsic scatter in the
center-excised luminosity-mass relation is remarkably small, being undetected
at the <10% level in current data; for the hot, massive clusters under
investigation, this scatter is smaller than in either the temperature-mass or
Y_X-mass relations (10-15%). Third, the evolution with redshift of the scaling
relations is consistent with the predictions of simple, self-similar models of
gravitational collapse, indicating that the mechanism responsible for heating
the central regions of clusters was in operation before redshift 0.5 (the limit
of our data) and that its effects on global cluster properties have not evolved
strongly since then.
