Depends on what you do. If you track the car, most groups want tires three years old or less. If you just drive it, and I mean really drive it, you can probably get 15 to 20 K miles out of the rears and more on the fronts.
Why not look at the battery thread on the Forum. Everything is there. Put 2 or 3 blankets/towels down and double them up. If you think you are too weak to pull it out or drop in, get a helper.