Thank you, Zan. As for me,
I always like to hear crtiticism with such well grounded arguments 
Fresh view are often able to notice much more defects than the accustomed one. So, i modified my 3d concept scene with your improvements of sizes:
Poor house\store: w=5 l=7 h=5
Common House: w=10 l=10 h=7
Big House (2- or 3-storey): w=15 l=15 h=10-15
Hall (3-storey or with very tall ceiling): w=20 l=20 h=15.

About stalagmites... Honestly to say, i think it's not real to have such amount of stalagmites in one place. How their formed? Where are their stalaCtite's twin-brothers? Are they on 1st level ceiling near Azure sun?

Then the drops of mineral's solution must to tide over 35 kilometers from 1st level to 6th level

.....
Also, I think
it's little wrong to compare big PS-stalactites with real stalactites. The diameter of my 3d stalactites match your references, about their top...you right, klyros couldn't to remove'em...Got to think up something. ..Or may be dwarves helped them? How knows - it's PlaneShift - a magic world.

Yesterday i thought up that
we can substitute stalagmites to mountain bed.... damn how many beds in english with different meaning?!!...
So, it can begins from cliff, continue to the last small ROCK and walk off underwater. Rocks (ex-stalagmites) can be connected by arcs wich were made by sea waves.
About reefs - will it be Rock reefs or coral reefs?