I think the Hexagon was simple a design choice for a high recognition factor. The same with the golden light. The concept arts and this "world" can live without this elements.
Bethesda's level designer's map. http://bethblog.com/?p=336 Not only is it pretty tough, it contains a couple of new elements that weren't utilised in Valve's levels.
Just thinking about the canister, if its on the underside of the gun then that would suggest its some kind of gaseous element whereas if it was attached above it is more of a fluid.
Yea, face anatomy needs way more work on the sculpt. You have the silhouette, just not the medium forms. There's elements like the philtrum that are completely undefined.
So definitely multiple angles for everything... thanks! Is it common to see a page like these, followed by more pages showing individual elements standalone and with multiple views?
Impressive concepts, your breakdown of individual elements would really be an asset to a 3D artist and it is no wonder those sets turned out so well. Congrats.