I've been orbiting this array of technologies lately - 3d printing + silicone, and also epoxy resin - so this is all really useful info for me. Your comment about having to figure out working processes by trial and error rings true. I'll be sure to bear beeswax in mind - maybe it'll work some magic on epoxy as well.
In the spirit of reciprocal knowledge sharing, I've been using filler primer spray or smoothing prints. You're probably aware of it already, but it seems very underrated in the 3d printing community. Sands to a mirror finish amazingly quickly and easily, especially under running water. Obviously that's not a body safe surface, and I don't know what effect it would have on silicone curing, but still - one worth keeping in the toolbox.