Can a rear wheel hub assembly (with disc brakes) from a 97 Legacy be installed on a 98 Forester (along with the proportioning valve) and if so, what needs to be considered? I want to eliminate the possibility of a rear wheel bearing failure and I have a nice 97 in the Men's Mall (Pull A Part) close by to pick from.

Just did exactly the same thing over Christmas. Swaps over just fine. Make sure the donor hub has the wheel speed sensor intact or it's going to cost and cause headaches. Instead of fighting with the lateral link bolt just buy a replacement bolt at the dealership and cut the head off and drift the rest of the bolt out. Might help to have a spring kit handy for the parking brake as well. One of my retainer springs snapped when I went to remove it.