With only 51K, I would expect that the tires are still original. If you only buy 2, put them on the rear. Smaller diameters on the rear will mess with the traction control and AWD, as the systems think the rears are slipping.

First, find out what is wrong with the suspension that is causing the wear.

I like the vinyl steering wheel as it is very easy to clean. But I understand your dilema. The top of the line car shouldn't have a vinyl wheel. Call the junk yards and ask for a wheel from an "R". I would imagine 2004-07 fit, but I am not in the measurement business and until recently have never even removed a steering wheel - easy to do, by the way.

You could disconnect the rear prop shaft, BUT, that changes the handling a lot on wet roads. Torque steer is back with a vengance when the light pressure turbo kicks in. You would need to unplug the Haldex system, which might mess with the other computers. Yes, expect up to 2mpg increase with FWD only. The earlier non-Haldex systems were simpler to remove and put back on.

For tire facts go to TireRack.com and check their surveys. The Japanese make some decent tires that are very quiet.