Although Sligs are gender-neutral, they have a male personality - in a similar way to the Mudokons. Skillya seems to be akin to Sam, the mating male scenario seems unlikely, since we haven't heard about that at all. The Sligs do look incredibly similar so far (although this could be due to lack of technology at the time of the games), so it might be potentially possible that they are all cloned? I'm not sure.
It's true that Sligs aren't quite like hive creatures. They smoke, socialize and gamble. However, keep in mind the fact that there are many creatures on this world who act in unusual ways and display strange behavior. There are animals which do not fit into one specific animal kingdom. Example: Platypus (classed as mammals) lay eggs and milk is produced from their sweat glands!
I would think of Skillya in a similar way to the way I think about Sam. I would probably write about Skillya in the same way, someone who is mentally devoid of emotion, has been pushed to the limits through chemicals and is ready to snap at anything she deems 'wrong'. Slig soup must be nice if she enjoys eating it a lot
(Yes I love Sligs!)