Their mini station appears to be a small habitation module with a multiport docking adapter. Their drawing is preliminary and may not resemble the final configuration.

http://www.mirstation.com/pressrelease_4.html

The station design appears to be quite small with little room for internal storage or equipment. It might actually require a Progress vehicle be docked to it to provide for consumables storage when the station is inhabited. It might not even have an independent propulsion system but instead depend on the Progress to boost the orbit. That's actually pretty clever and a smart way to reduce costs. It does look like the station could be expanded over time by adding more modules. My guess is that the whole module and docking adapter are designed to be launched with a single Proton booster, so the combination will be limited to about 20 metric tons. It would be big enough to hold some batteries and gyrodynes for electricity and attitude control along with a minimal living area. They'd probably be pretty Spartan quarters but the view would be terrific.