  We study the extremely polarized two-component Fermi gas with a mass
imbalance in the strongly interacting regime. Specifically we focus on the
experimentally available mixture of ${}^6$Li and ${}^{40}$K atoms. In this
regime spin polarons, i.e., dressed minority atoms, form. We consider the
spectral function for the minority atoms, from which the lifetime and the
effective mass of the spin polaron can be determined. Moreover, we predict the
radio-frequency (RF) spectrum and the momentum distribution for the spin
polarons for experiments with ${}^6$Li and ${}^{40}$K atoms. Subsequently we
study the relaxation of the motion of the spin polaron due to spin drag.
