Basically, what I’m having trouble with is the variable parts. I tried Google and Orthodoxwiki, but that just got me more confused as it seems that these are just a million different categories of hymns and prayers, with no attempt to explain their liturgical role or significance.
Since the Horologion was never conceived for use by laymen, I can understand why the rubrics aren’t clearer. But I did hope that there would be at some guide out there.
Also - as far as I’m aware there only 2 English horologions still available - The Great Horologion from Holy Transfiguration Monastery, and the Unabreviatted Horologion from Jordanville. There’s also an Antiochan Liturgion, but that’s aimed at clergy and not reader services. Oh, and also the Old Rite Horologion, but I don’t think that’s in print anymore. So really there’s two options - Slavic or Byzantine. I can’t recall (and if someone can, I stand corrected) a Slavic Catholic church that doesn’t follow the Roman Right. So the Byzantine choice seemed the obvious way to go.