W.r.t. checking the config file at runtime, the Linux kernel has this nice feature called `inotify` which lets you react to filesystem changes instead of periodically polling for them. Might be worth a look, if you haven't heard of it yet!
I vote the in-game asset creator. I think you, personally, as the author, should focus on making the best game, and if people want it badly enough on other platforms, they'll eventually just contribute :P
