  This paper is concerned with the Cauchy problem of Navier-Stokes equations
for compressible viscous heat-conductive fluids with far-field vacuum at
infinity in $\R^3$. For less regular data and weaker compatibility condition
than those proposed by Cho-Kim \cite{CK2006}, we first prove the existence of
local-in-time solutions belonging to a larger class of functions in which the
uniqueness can be shown to hold. The local solution is in fact a classical one
away from the initial time, provided the initial density is regular. We also
establish the global well-posedness of classical solutions with large
oscillations and vacuum in the case when the initial total energy is suitably
small. The exponential decay estimates of the global solutions are obtained.
