Bimetric theory describes a massless and a massive spin-2 field with fully non-linear (self-)interactions. It has a rich phenomenology and has been successfully tested with several data sets. However, the observational constraints have not been combined in a consistent framework, yet. I propose a parametrization of bimetric solutions that allows to combine the various observational constraints in a straightforward and unique manner and present first results from supernova data. In the second part, linear instabilities of cosmsological perturbations are addressed. I argue that they are an artifact of the Vainshtein screening mechanism and present some evidences.