Thanks for those comments. I should note for anyone listening to the link that last few measures of whatever you're hearing (it changes as I edit it over time) will be likely to be full of unintended notes, as they are likely to be just the notes I throw down at first with the intention of fixing them up in post so to speak... ;)
I see what you mean about the dissonances in the first line. The one in the fifth bar seemed alright to me, but I'm having a flashback to my experience in music theory many many years ago where things that sounded "fine" to me at first soon turned into glaring errors as I got more and more habituated into the rules...
As for altering the theme, you mentioned several types of alterations which I will look up, but here I'll ask, is basically _any_ alteration "okay" or should one stick with a list of alteration types which includes the ones you listed?
I'll not be refering to this thing as fugue or fugue-like anymore. But I think I'll stick with the conceit of having all the voices go over the same theme at different times starting on different notes. (Except I do think I'm hearing in my head a single "soprano" ranged voice playing a melody over everything else which I'll add in later.)
As for what style I'm writing in, I haven't been sure what to think about that. Once it goes into minor I've got some chords in there I think of as "jazzy" (not as in actual jazz style but you know... jazz influenced...) which I suspect are not allowed in classical style but which I think I'm going to leave in. For example the major second in bass and tenor in measure 23... Maybe I'm wrong about that though... Actually maybe what I should do, in order to be disciplined, is be very strict in this piece--but feel free to make an alternate version which isn't so strict...)
When you say it's not necessary to change key signatures, are you making a point just about notation, or do you mean something about the music itself?
Thanks again for all your comments.