I'm pretty sure you can buy multiple copies of items. And it would count as a seperate item anyway, so yes, you could purchase a box after purchasing the expansions by themselves.

Oh. Well probably not, unless Stardock in all their benevolence decide to give you a discount if you have the expansions.

It's possible, but I wouldn't count on it.

@Mooster I've taken my Sins disc, which I got through Impulse, and installed it on one of my comps that doesn't get internet (it's broken, but a laptop is still more portable than a desktop). Works fine on my other comp. Same thing goes for Demigod, which I also ordered through Impulse. And finally, maybe I want the concept art, manual, soundtrack, or back up disc. There are many reasons for wanting a box, but that isn't the point of this thread.