That's a beaut Andy.
Regarding the bomb arming - the cables were anchored to the pylon and intended to remove the safety pin once the bomb was released. If the in was removed on the ground, the slipstream, once airborne, would cause the impellor to rotate, thus arming the bomb, not a desirable situation.
If a bomb had the nose fuse, as per your model, I'm not sure if a tail fuse would also be fitted, although this is very possible, especially if the tail fuse was delayed action.