From the image you can see that the room is fairly large. It is not only an airlock but a locker room where the Vuduri get dressed or undressed to go outside or into space. Normally, there is not a sarcophagus in the way so if the Vuduri want to go outside (having already dressed), they simply open the inner airlock door, enter the chamber, then lock the door and evacuate the room and exit by the door shown on the bottom.
There are lockers on the right and benches if they need to dress. The interior of the star-base is on the top side. The rectangle labeled "Airlock to Base" is the bulkhead where Rei first set eyes on Rome. The wall labeled "Monitoring Equipment" is the display panels and grille where Rei first encountered OMCOM. This is also the chamber where Rei almost met an early demise at the hands of Estar but luckily his wits and reflexes saved him.
Tomorrow: Rei's home away from home - the "apartment" Rei was assigned during his time at the base.
Entry 1-205: July 18, 2013
Skyler Base: Why rings?
(This is part of the continuing series about the design of Skyler Base)
The answer is: that's the way the Vuduri build things. This is seen numerous times in Rome's Revolution, The Ark Lords and Rome's Evolution. The Vuduri decided that the circle is the optimal geometric shape so all their cities are circular rings. It is only natural that they build their base in this way as well.
There are two main corridors going north-south and two minor corridors situated diagonally. The idea is it should take you the least amount of time to get there from here. You can see the basic layout here: