The two wheels on the stbd side are the bow and stern dive planes.
The helm is actually in the navigator's nook (tight quarters for the nav and the on-watch helm)
There may be compressed air tanks in the control room, but the large outboard spaces missing there are the midships diving ballast tank. I've got a tank schematic here somewhere...
http://www.dreadnoughtproject.org/pl...lan_100dpi.jpg
This is the internal tank arrangement, and there's another (I think on that site) with the same paper and ink that shows hull details for dry-dock and external repair purposes.
I had a similar thought about the CO's rack, but I felt there was a lot of unused space on the port side aft of the radio room, and the schematics do seem to indicate *something* should go there. Also, the Vesikko can't be considered to be a 100% model for the type IIa, as it was a prototype and had different surfaced and submerged characteristics (among other things).