I am making royal icing for a cake with meringue powder. If I make it tonight to use for tomorrow should I store it at room temp or in the fridge? Also, once it's on the cake if it's then refrigerated if it gets bumped will it crack the writing I did with the RI?

You can store iron the fridge just make sure u put a damp rag on top then cover it tightly. Once you write with the ri do not touch or bump into it cuz it will crack! Good luck!