It is appropriate to rebush the idler arm and other steering components only if needed. All parts except the steering damper can be diagnosed in-situ with simple techniques - most with the car on the ground. Have someone gently turn the steering wheel back and forth until just before the road wheels move - engine off. Observe all parts of the steering linkage to see what doesn't move when it should - or moves in a direction other than what it should. The idler arm is located symmetric in th linkage to the pitman arm coming off the steering box.
The damper can be checked for operation off the car - pretty easy to remove. The damper will NOT cause looseness in the steering - it is there to mute road shock back through the steering wheel.
Worn suspension parts can cause problems with steering, and may be more difficult to diagnose. If you have a problem, throwing parts at it could get very expensive in this area.