Looks good so far! I know Lukas ((its ljcrzynfree19 btw :) )) and Omithiel are really great builders. I dont know the others, but I am sure we will have an awesome looking capitol.
I'm not sure if you meant for this post to be a place for suggestions, but I wanted to give my opinion if I may. Most of my ideas I have been playing around with on my single player worlds in 1.8 mostly, so not sure how it would look using some of the 1.9 options. (I can't stand playing without a texture pack anymore lol)
-lava behind either iron bars or behind nether fences to light the main hall's walls. I understand dwarves like caves and dark places and all, but I think torches would make it look too bland and glowstone when overused doesnt look good. Torches in the general areas would be ok though, just think the main hall should be majestic, you know? If not that, Omithiel has some really good carvings in Alras that could be made using this lava method, I think it would look good and have the added benefit of lighting up the hall.
-Algrim had what I thought was a good idea for petrified trees in a city we worked on before. I'm thinking we could just make a large tree using native's excellent guide as a reference. If we used mossy cobble for the leaves and stone for the trunk and branches, we could make a cool looking one i think. We'd have to mess with it a bit I think though to make it look good, but it might be a good RP source. You know, have the dwarves life force tied into it, it grows with more dwarves being "born" on the server etc. I dunno, just a thought.
-I really like the gatehouse, and use of the stronghold stone, but maybe a few blocks here and there of the crumbling or mossy stronghold stone? Just to give it a bit more character. I do understand if you want to make those places look well kept though, since these places would be a priority for the dwarves to keep maintained.
Thats just my 2 cents, but I think you have some great builders backing you up, so I'm not at all worried if you guys dont use or like my ideas. If I get the chance, I'll take some screenies of what I have in my world to show what I mean if the ideas are liked :)