Now about the dwellings. Ar, Drink, it's up to you to decide. I just suggested it. Since the race won't suffer from gold fever, we'll proceed from that. I support the crystal; it's a suitable resource for the race.
Illithids... It occurred to me to type this word into Wikipedia... I got a rather interesting result; if you're interested, read it here
Why not make the Central Brain their place of residence? Or rather, not exactly a place of residence, but, let's say, a structure that provides an increase in the number of these illithids)) I don't have any other ideas yet.
Bow down and hear our cry,
Our earthly rulers falter,
Our people drift and die,
The walls of gold entomb us,
The swords of scorn divide,
Take not thy thunder from us,
Take away our pride.
G.K. Chesterton: English Hymnal