Hi Spica, congratulations on being one of the most innovative developers present on XDA.
I'm still not done with my "other app", but upon reading this thread I cannot help getting a lot of ideas for a GUI. One of the challenges is of course that the options present in /data/spica will change a lot over time, so writing a GUI which has the options hard-coded is not an alternative. So the best way to go about it would be to have some kind of definition-file... BUT, if no definition file is found the app has to scan /data/spica AND probe each entry for acceptable values, then build a definition file from that. (The point of using a definition file is that is is 1) faster and 2) should have human-readable descriptions.)
It should go like this:
1) Look for the file "spicaconfig" in sdcards and local/data.
2) Scan /data/spica for options present.
3) If new options found, let user add a description and/or allowable values, if not probe new entries for acceptable values.
4) Build user-interface.
Quite straighforward and very user-friendly since the same app-version can be used with different kernel-versions, and you can of course include definition-files with each kernel (with more detailed descriptions) or the users can make them. (Definition-files should come in language-variants as well.)
The only problem I foresee is the lack of a known default value for the different parameters. There's no point in storing the first value read as the default value, since a later kernel-revision might change it.
I therefore suggest that you somehow include the default read-only value for each option, for instance 340000 in /data/spica/defvalue/gpufreq. (This way you don't have to include a page of descriptions each time you make a change either)
Since the default values are already present in the kernel it should be a simple task to expose them.
As stated I'm still busy with other stuff, but if anyone else wants to take these ideas and run with it, feel free. If not I can probably attend to this is a few weeks time (but no promises.)
Good luck with kernel, looks promising.