I don't think it would be easy to get those alternatives in.
Part of the problem is to retain RAW independence, i.e. have the plugin derive categories from the RAW contents, rather than hard code what they are. It would probably be easier to introduce a Fuel category, although I can't say offhand if there's an easy way to determine whether an input is fuel or part of the product (reactions are messy, with poor indications of what's what).
It's even harder for your metal case, as you're not satisfied with just any weapons grade metals, but only want the top ones (and silver can be argued to be the "best" one for blunt weapons at that). Leaving it up to the user to "build" the the lists would obviously remove the burden from the tool to determine what to look for, but at the cost of building some convoluted Boolean logic construction UI. It can also be noted that coal is represented by several mineral, while metals are derived from (potentially) several mineral, so it wouldn't be possible to combine minerals and metals at the same time.
The Matching World Tiles should be that, i.e. the number of world tiles that have at least one match in them. The number starts high as the first pass counts all tiles that are not incapable of having a match (e.g. requiring clay, and there's no clay in any of the mid level tiles). The detailed pass then removes the ones that do not have any match in them.
Unless there's a bug, each matching world tile should be marked on the middle map (the one labeled "Region" by DF), first with a yellow "X" after the tentative pass, and then a green one when the final check has been made (assuming there was a match: otherwise the marker is removed, of course). If those markers are missing, there's a bug somewhere.
It can also be noted that there are more yellow markers on the first search than on subsequent ones: that is not a bug, but a result of detailed examination of tiles carrying some info back to the preliminary phase data (it starts out based only on what the geo biome of that world tile and its surrounding tiles have, but e.g. in the case of clay, if one adjacent world tile has clay, the tile would not be marked as "definitely no clay", but if a detailed examination showed there wasn't any (due to erosion or no mid level tiles having that neighboring tile's geo biome), the info is updated to "no clay present".
The reason there are no indications on the World map (the rightmost one) is that I haven't been able to replicate the logic DF uses to squash multiple tiles into one for display: I've come fairly close, but that's not good enough.