I have read that a crew space which is cramped for a submarine is much more spacious in a spacecraft in free fall. The ability to float makes more of the area usable.
How do inflatable modules do when it comes to weapons grade radiation shielding? They are about as effective as a bullet-proof vest composed of wet toilet tissue.
You could use the radiation shielding for the outer wall of the habitat module, but the stuff is so heavy it would cut down your payload capacity to the point where you could not carry any crew or weapons. According to my figures anti-radiation armor
starts at four-fifths of a metric ton per square meter of armor (796 kg/m^2). That's basic armor, if the nuclear warheads are really flying you'll need thicker armor.
Atomic Rocket: Radiation
(scroll down to section that begins
"In Space Propulsion Analysis and Design they give the specs on a typical shadow shield."
You'd probably be better off putting your radiation armor around the control cabin.
Inflatable module skins are not particularly resistant to weapon lasers either, but you can get away with using sheets of carbon for armor.
Atomic Rocket: Space War: Defenses
Carbon sheets can be placed over the inflated skin, or over a titanium skin if you don't want to fool with inflatable habitats.