I can't offer you anything concrete. I did however, have a
fairly benign cult of Oramus in one of my games. I say fairly because their interests largely centered around supernatural architecture that bent space in impossible and deeply confusing ways. The city-state they were based in was ruled by Sorcerers who were very big on demon-summoning and binding, and the unusual architecture of the Orameans facilitated summoning. Unfortunately, it also caused many more unbound demons to appear in the city spontaneously as well, which the Oramean cult did not really intend but aren't really overly concerned with fixing unless they're paid to do so. Their main concern, however, was to build a pathway to Malfeas within the confines Oramus's prison of wings. It certainly wouldn't be enough to free Oramus, especially from himself, but it would allow them to consult with the object of their worship on matters of space and time, which was their central fixation. So they were a bit like the College of Byrgenwerth from Bloodborne, albeit somewhat less prone to unethical experimentation in their pursuit of understanding.
Unfortunately, an Abyssal found the pathway the cult was using, and largely felt that a heavily bound and helpless Oramus would be the easiest of the Yozi to kill. And so, enter the PCs.
So, my interpretation of Oramus worshippers is that they are largely a collection of eccentrics with a scholarly bent, with a particular fixation on metaphysics and Oramus's own Paradoxical nature. There weren't any commandments or rules per se, so much as just a general policy of 'contribute to our growing body of knowledge, don't bring us negative attention from outsiders, and defer to your seniors'
I borrowed kind of heavily from Pythagoreanism for the little details and maybe it can help you too:
Pythagoreanism - Wikipedia