They were generally bigger than your average humanoid, reptilian with a tail and fairly scaly with differing colors. Ajute cast members were red if I remember correctly and those were the only ones that really made an appearance aside from the generally less cast oriented QIS employees that popped up from time to time.
In general they were highly religious, devoted to their emperor, and worshiped at the few oasis areas on their desert world. They don't really hold much love for the Jaaq'tah even though both races are reptilian particularly because the Jaaq'tah attack on Ralfaris put the planet into a nuclear winter, destroying many sacred areas.
Qel'norans were generally okay with the Yamatai Empire when it first conquered their world, but were later engineered into distrust of the Empire by Sijik who in turn engineered the takeover of QIS after Wazu left. He then furthered his control over the planet by having QIS declare itself an independent corporation rather than one under Yamatai law which caused Yamatai to try and explode Ralfaris.
In the mean time Sijik has been deposed of, but they still generally distrust the Yamatai Empire. QIS has been reorganized as the United Industrial Sector which included a large amount of Ayenee based population and business. They also had run ins with the Re-Hash, Machine matrix, NTS, and covenant from Ad Infinitum (which would later be known as Galaxy's Edge which Yamatai participated in for a while). The most accurate description of the Qel'norans during Ad Infinitum would be Freakin Rich as they had accumulated more wealth in resource points than all other factions combined though they generally stayed out of wars after their interference in the attempted Genocide of the Re-Hash. Though this and what happened in Ayenee is getting away from the Qel'norans and more towards the exploits of QIS/UIS.
As for Psychics, some Qel'norans did have mental abilities but not all of them. They also came in a wide variety of personalities though the Ajute cast member on the Yui (played by John) was generally the strong silent type. There did seem to be a trend of the bigger they are the more aggressive they got but that isn't exactly Cannon. For the most accurate information about the species you'd have to talk to John.
