Now that you mentioned it, I'll definitely start trying to add some tileset editing features into the editor. I'm still trying to think of a good way to implement it. The game doesn't store tilesets as a whole but instead keeps the sprites, metatiles, tile behavior, palettes, and other things in different parts of the rom and throws them together for each level. The "themes" in the editor were actually hard-coded to give the appearance that the tilesets were better organized. This is why it's a bit tricky to implement. What I'll probably end up doing is auto-generating themes from the rom as it's loading. That way, it'll be easier to maintain some sort of organization. The themes would no longer have names but would be assigned numbers.
The coin counter idea, on the other hand, should be fairly easy to implement. It'll be included it in the next release.