Non helpful answer: A mysterious, vague number that balloons in size with new content.
Hmm... I always thought the station was made up of a multitude of rings connected to a central pillar. I don't know where the ship hanger plays into that though, but it's unlikely to extend beyond the diameter of the rings unless it's the base of the pillar... If we knew how long it takes to traverse one square, you could at least figure out the general size of the shop ring's length. The residential deck could be a floor of the central pillar + the connecting rods to the circle... Whether the shop ring is one of the bigger ones, and the number of rings is unknown though, so guesstimations are limited.
As for why I see the construction that way, one poster on the old forum threw down a bunch of sketches of the station and Mhen'ga, and Fenco seemed quite happy with the visualization.
...Since Fenco said capital ships are a go and that Tavros is equipped to support them, Tavros would have to be pretty freaking huge, or the ship's gravity well would break the station.