Many of your questions will be answered very uniquely to your own case, triwinggirl, in fact you may not need the replacement surgery at all. But there have been amazing strides forward in joint replacement surgery, if that is recommended. There is always some bone removed and replaced with titanium parts, but they rarely have to remove and replace the entire joint any more, so recovery is not as difficult and long as it used to be. Also, they will have you up and walking with crutches within 24 hours in most cases. There will be therapy recommended afterward, but how much you need of that will depend much on what you do at home to help your progress along, and how fit you are to start with. It is different for every individual.
I'd strongly recommend you see an orthopedic specialist right away for an evaluation. He/she will be able to give you more specific answers. And, as I said above, you may not even need the replacement surgery....... an arthroscopic repair with minimal down-time may be the recommended solution!