The sub-frame bushings are what keep the front and rear sub-frame where they should be. Ideally you would use a solid bushing like the aluminum ones from SHO Source, but the factory rubber bushings isolate the sub-frames from the unibody to reduce NVH providing a quieter and more comfortable ride. As the bushings wear the sub-frames can shift around a little bit. Being that the control arms mount to the sub-frames, I think you can see how this negatively affects handling and ride quality. It's not a big deal to do them after the fact, but replacing them should be considered routine maintenance.I am actually in Florida and pretty much zero corrosion. Can't the subframe bushing be changed after the fact? Do they cause handling problems?
The front half shaft nut preloads the bearings, squeezing the inners against a "crush spacer". If the nut comes off, the bearing inner races are free to come off the spindle. I know of only one case personally. That was a parts car where the half shafts were removed. Then they towed the car to mow grass and a front wheel fell off.You are talking the rear axle nut?
I don't see how the front coming off can lead to the wheel coming off with the hub?