We investigate the carrier dynamics in graphene utilizing the free-electron laser FELBE as a source of low-energy photons. Polarization resolved pump-probe experiments with linearly polarized radiation allow us to disentangle the role of electron-electron scattering and scattering of electrons with optical phonons. Applying magnetic fields perpendicular to the graphene layers results in a non-equidistant Landau ladder. Pump-probe experiments with circularly polarized radiation can address individual transitions. We find evidence for strong Auger scattering and discuss the implication for potential graphene-based Landau-level lasers.