  A combination of the memory function formalism and time-dependent
density-functional theory is applied to transport in dilute magnetic
semiconductors. The approach considers spin and charge disorder and
electron-electron interaction on an equal footing. Within the weak disorder
limit and using a simple parabolic approximation for the valence band we show
that Coulomb and exchange scattering contributions to the resistivity in GaMnAs
are of the same order of magnitude. The positional correlations of defects
result in a significant increase of Coulomb scattering, while the suppression
of localized spin fluctuations in the ferromagnetic phase contributes
substantially to the experimentally observed drop of resistivity below T_c. A
proper treatment of dynamical screening and collective excitations is essential
for an accurate description of infrared absorption.
