I have been loading and casting my own for years and especially since starting using those 500gn black powder 45-70 loads. I set up my pot just outside the garage door with a fan behind me to blow out the fumes and flux smoke. I wear a face shield which keeps most smoke and fumes out. I flux with sawdust so I can see the smoke and the fan keeps it blowing away.
I preheat the Lee dual cavity molds (use 3 at a time) on an electric hot plate covered with aluminum foil. I keep the molds sprayed with Kroil when not in use and it burns off after the first several casts. For the big bullets it takes 5 or 6 casts to get the molds hot so there are no wrinkles. For the 358 diameter wad cutters I use a Lee 6 cavity mold and the bullets come out great much faster, usually only one or two drops.
Here is a great site that seems to cover the whole casting game the best I have seen.
Cast Boolits - Dedicated To The World Of Cast Bullets!