C-rescale is described, including reference, in the manual here:
https://manual.gromacs.org/current/reference-manual/algorithms/molecular-dynamics.html#stochastic-cell-rescaling
First order coupling algorithms usually do not have issues with stability due to oscillations, so choosing the value for tau is not so critical. But tau_t needs to be small enough to effectively remove energy drift due to integration errors. tau_p should not be too small, as scaling the volume too fast might cause instabilities.
My advice would be tau_t=1 ps and tau_p=5 ps for nearly all atomistic simulations.