Surprisingly, there was only one line to add to fix the issue with Random Factorio Things. The mod looks a little.. superfluous to me, considering other mods add very similar entities, and implement them in much more balanced ways, so I won't be contributing full compatibility (i.e. long-handed versions of all nuclear inserters) and I can't make the crafting menu as pretty as with other mods, but it won't crash on load, so that's probably all that matters.
As for the multiplayer sync bug; I currently have no simple way of testing with multiplayer, but that sounds like an issue with Factorio itself. Especially since there are literally only 2 startup options, and both are simple true/false options.
Anyways, fixed compatibility with Random Factorio Things as of v3.0.3