1. The queen has a male Noble consort.
2. A Danian queen can force control upon her subjects if she wishes. A M'arrillian interfacing with the queen can thus take advantage of this
1. Fluidmorphers were once held in high esteem and formed the bulk of the invasion force into Perim. Kha'rall were not mentioned. Yet, in modern Perim, Siril'ean is considered to have useless powers before the invasion of the drylands. So something happened during the period of the M'arrillian imprisonment that ended up with Fluidmorphers being considered useless and Kha'rall being promoted. Something in the Deep Mines, perhaps?
2. Oligarch is the title of the leader of the Chieftain council. So no, not all of them are Oligarchs, only whoever is leader of the current Psikoom.
3. Doesn't have to do with their society, but Oligarch Pheren'tal was the only tribal leader to be described in detail in the Khilaian Sphere(Kehn-Sepp's only description was "crimson face" and "majestic wings"). Here is the blurb on what she looked like
"The M'arrillian ruler was as beautiful as ever, her skin a shimmering blue-green, her three eyes like triangular pearls in her oval face, her tentacles long and slender and tipped in delicate barbs. She was exquisite, but her beauty masked a mind as sharp as any in M'arr, and a will stronger than the waves themselves". I found her description interesting because it gives us some insight into what M'arrillians find beautiful and also the fact that she seems to bear some form of resemblance to Aa'une(the more humanoid facial structure and the tentacles' description)
4. M'arrillians act just like any other tribe. They bicker amongst each other, vie for power, call each other cowards, and do other things that make it seem like they are not inherently evil. Their conquering spree seems to be a case of power corrupts more so than anything else