The back is solid aluminum, no back plate to detach, however it's the same size as back plate on the iphone 4 so in theory anything that is made to stick to the back of the iphone 4 will stick to the back of this case. We went with a full back plate because it protects the iphone much better then bumper style cases, however we like the look of said bumper cases so we gave you guys the choice to make it look like a bumper/2 material case.
The spring mechanism is set into the case so it shouldn't catch anything. Its much harder to see those springs in real life then in those photos.
Ah, got it. Now I understand what you meant about the camera cutout. Sounds good.