Hello again. Sorry for the delay in my response.
I appreciate the words of warning. Regarding this thread, I kind of considered it a fleshing out of particle education, such as, "Well, if I know about wa, de, yo, etc., then I should know about other often-heard, if informal, particles such as ze and zo."
I've been working on a lot of the fundamentals on my own (no classesツ―just casually paced self-education, though admittedly there's been little lately). I've been focusing pretty heavily on grammar for a while and the questions I ask are often branched from something I've learned and want an example of (the books I use aren't very thorough) or somesuch. It does help me to learn better and fit pieces together. There is indeed a pattern to the seeming randomness. I understand that I can't get a very thorough understanding of things like this yet, but getting the gist of them is pretty important to me.
Thanks for the encouragement. I have applied at The Yamasa Institute for April and am confident about my odds. If accepted, I'll start there in April. Assuming that I can get an eikaiwa job there, I'll be set.