Andy,
Those exercises that Jim posted the link to....you can start those now. They help to strengthen the pelvic floor muscles which will get you continence sooner after the surgery (if you wind up with a neobladder).
Also, they take your prostate during the surgery so there may be a couple of other things you want to spend time doing before the surgery.
I'm sure Jim will give you lots of great post-op advice when you see him. I will just say walk, walk, walk! That gets the intestines going and that is the key to being allowed to go home (and to feeling better).
I'm not sure if I mentioned this one possible complication either. Fluid has to go somewhere after the surgery. Sometimes, some of that fluid goes to the scrotum and one can wind up with something the size of an American football there. If you notice any enlargement, use a pillow to elevate the area.
I forgot about that until recently when a relative of someone who just had an RC asked me about it. It's not anything to worry about but I can tell you from personal experience that it can be pretty darn scary if it happens and you didn't know it was something that could happen!
Best of luck on the surgery!
Mike