You usually buy it as a slurry in water that is 50/50 wt% RaNi. To get the maxium activity out of it you should wash and decant with absolute ethanol a few times to remove as much water as possible. Ethanol (sometimes methanol) is the typical solvent for these reaction.
It's a competent reductant for reducing carbon sulfur bonds on it's own. It can also reduce alkenes to alkanes if you use stoichiometric amounts, but for that purpose people often use a catalytic amount of RaNi and a balloon of hydrogen gas. The reduction of alkenes is slow relative to the reduction of carbon-sulfur bonds and sometimes you can remove sulfur in the presence of alkenes.
There are some other funky reactions that RaNi will do as well. There is at least one example of enantioselective carbonyl reduction with tartaric acid as a ligand. That's a rare thing for a reagent that seems to be a heterogeneous catalyst. I'm not familiar with speculations about the mechanism of the enantioselective reaction though.