Wgs84 data is assumed for distance calculations. If you need to convert your data on the fly, I typically recommend proj4js.

Maybe you could document that more explicitly. Basically defining the scope of the project and where to look for complementary tools like proj4js and rbush for instance.

I'm talking about buffering and such, "1 mile" isn't a sensible measure in latlong. I didn't carefully analyze the code, so maybe I'm just missing something.