Hi Cathy,
There is not an easy answer to your questions since every person, surgeon and surgery is unique. I can only tell you what my experience has been. I had both hips replaced in May '05 due to severe OA at age 53. I was in very good physical condition so I breezed thru my recovery and was able to return to most all of my athletic endevors within months. At my 1 year checkup, my surgeon lifted all restricitions. While I no longer run competetivly or much at all for that matter, I do ride (eventing) competetively, mnt bike, kayak, rollerblade, x/c and downhill ski, hike, yoga, weight lift ect. I do not think about my hips much at all when being active, they do not bother me. But I am of course, concerned about their lifespan. However, there is not too much I can do about it, other than trying to stay strong to protect them and give up running.
If I can give you any advice, it would be to find an outstanding surgeon who specializes in THR if that is what you need. Skill is everything! My wonderful surgeon does more than 360/yr and is very well respected in his field. On top of that he really listens to me and is very empathetic to my needs. He did an outstanding job on me.
Next, I would tell you to stay as fit as possible. You are pretty much down and out now it sounds like, but try to stay as lean as possible and keep your upper body strong. Do not wait until you have lost all your muscle tone.
Sorry about your riding accident. It is always on the back of my mind. Good luck getting back on your feet.
Andrea