In this article, we study the effect of various parameters on the estimation of radiation temperature inside an indirect drive ICF hohlraum and also study the hydrodynamics of aluminum and gold foils driven by the hohlraum radiation. A multigroup one-dimensional, radiation hydrodynamic code is used for this study. Opacities are calculated using a screened hydrogenic average atom model. We also investigate the opacities of Au-Sm and Au-Gd mixtures. It is shown that the mixing of two high Z materials can lead to an enhancement in the Rosseland means, which is of direct interest in indirect-drive inertial confinement fusion. The radiation temperature inside a cylindrical hohlraum is seen to be strongly dependent on the number of frequency groups used. One group radiation transport underpredicts the radiation temperature. It is shown that erroneous results can be obtained if the space mesh in the hohlraum wall is not fine enough. The spectrum of the radiation inside the hohlraum is seen to be different from Planck, especially in the high-energy range. This may lead to preheating of the target. Hydrodynamics of an aluminum foil driven by the hohlraum radiation is also presented in this article. A scaling law for the radiation-driven shock-wave speed in the gold foil is obtained.