sorry, no fuge, though on my next big tank Im thinking of using one. I have a cascade 1000 on my tank now and it works fine, but I only have a 60 hex. I have seen people use "miracle mud" in their fuge, and the posts are always positive.
All depends on the functionality of the fuge, if your using it for pod reproduction then i suggest sand and live rock but if you are using it for macro algae for nutrient export and already have sand in your display then no substrate is needed.