Just a note on the string processing. I think Luca D, one of the more prolific plugin authors did something with string processing, but I am getting old and my memory is not what it was.
Might be worthwhile checking with him/on the old forums so you do not duplicate effort or waste your time.
Luca here... I mostly did stuff that involved file manipulations, but not this kind of "reverse token" parsing, so no time wasted there
Personally, i started with smaller, distinct plugins, but went on to aggregate more into a single entity (as long as the concept of the functions is roughly the same, in my case mostly file handling) so that i had not to duplicate a bulk of the code i was using...
Also, but this is just a speculation on my part, I was of the idea that when you start to mixing up call to different functions in your profiles, there would probably be a slighly small overhead if they were all on the same DLL, instead of split into multiple plugins